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Specific Gravity for a Solids Slurry

Environmental Engineering · FE Reference Handbook section

Environmental Engineering
12 formulas
10 exam-style examples
~60 min
All Environmental Engineering lectures

Handbook notes for this section

Definitions and conditions exactly as the handbook states them.

  • The volume of waste sludge for a given amount of dry matter and concentration of solids is given by

Core formulas for this FE topic

Definitions, applicability, units, assumptions and worked examples for each relation.

Worked exam-style examples

The four ways this section is written on the real exam — thoughts first, then equations, then substitution.

Example 1
Specific Gravity for a Solids Slurry — solve for specific gravity of slurry — Specific Gravity for a Solids Slurry

specific gravity for a solids slurry of sludge and water Given fraction solids by weight (W_s) = 0.2660; specific gravity of solids (S_s) = 1.9700; specific gravity of water (S_w) = 1.0060, determine the specific gravity of slurry (SG_s).

Given

  • fractionsolidsbyweight(Ws)=0.2660fraction solids by weight (W_s) = 0.2660
  • specificgravityofsolids(Ss)=1.9700specific gravity of solids (S_s) = 1.9700
  • specificgravityofwater(Sw)=1.0060specific gravity of water (S_w) = 1.0060

Find

specific gravity of slurry (SG_s)

Start with the thinking

  • The governing relation printed in this handbook section is Specific Gravity for a Solids Slurry.
  • Everything except SG_s is given, so isolate SG_s symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Specific gravity for a solids slurry combines the specific gravities of solids and water weighted by solids fraction.

Step-by-step solution

  1. Step 1 — State the governing relation:

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}
  2. Step 2 — Rearrange symbolically for SG_s:

    SGs=1WsSs+1−WsSwSG_{s} = \dfrac{1}{\dfrac{W_s}{S_s}+\dfrac{1-W_s}{S_w}}
  3. Step 3 — List the givens: fraction solids by weight (W_s) = 0.2660, specific gravity of solids (S_s) = 1.9700, specific gravity of water (S_w) = 1.0060.

  4. Step 4 — Substitute the given values:

    SGs=1WsSs+1−WsSwSG_{s} = \dfrac{1}{\dfrac{W_s}{S_s}+\dfrac{1-W_s}{S_w}}
  5. Step 5 — Evaluate:

    SGs=1.1565SG_{s} = 1.1565
  6. Step 6 — Check: returning SG_s = 1.1565 to

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}

    reproduces the given quantities, and both sides carry the same units.

Answer:
SGs=1.1565SG_{s} = 1.1565

Why the other options are there

  • 2.3131 — kept a factor of two that cancels in the correct rearrangement.
  • 0.5783 — dropped that same factor in the other direction.
  • 1.2722 — rounded an intermediate value before the final step.

Reference: FE Handbook — Specific Gravity for a Solids Slurry

Example 2
Specific Gravity for a Solids Slurry — solve for specific gravity of solids — Specific Gravity for a Solids Slurry (2)

specific gravity calculation for a solids slurry from a thickener Given fraction solids by weight (W_s) = 0.1390; specific gravity of water (S_w) = 0.9980; specific gravity of slurry (SG_s) = 1.1430, determine the specific gravity of solids (S_s).

Given

  • fractionsolidsbyweight(Ws)=0.1390fraction solids by weight (W_s) = 0.1390
  • specificgravityofwater(Sw)=0.9980specific gravity of water (S_w) = 0.9980
  • specificgravityofslurry(SGs)=1.1430specific gravity of slurry (SG_s) = 1.1430

Find

specific gravity of solids (S_s)

Start with the thinking

  • The governing relation printed in this handbook section is Specific Gravity for a Solids Slurry.
  • Everything except S_s is given, so isolate S_s symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Specific gravity for a solids slurry combines the specific gravities of solids and water weighted by solids fraction.

Step-by-step solution

  1. Step 1 — State the governing relation:

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}
  2. Step 2 — Rearrange symbolically for S_s:

    Ss=Ws1SGs−1−WsSwS_{s} = \dfrac{W_s}{\dfrac{1}{SG_s}-\dfrac{1-W_s}{S_w}}
  3. Step 3 — List the givens: fraction solids by weight (W_s) = 0.1390, specific gravity of water (S_w) = 0.9980, specific gravity of slurry (SG_s) = 1.1430.

  4. Step 4 — Substitute the given values:

    Ss=Ws1SGs−1−WsSwS_{s} = \dfrac{W_s}{\dfrac{1}{SG_s}-\dfrac{1-W_s}{S_w}}
  5. Step 5 — Evaluate:

    Ss=11.4260S_{s} = 11.4260
  6. Step 6 — Check: returning S_s = 11.4260 to

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Ss=11.4260S_{s} = 11.4260

Why the other options are there

  • 22.8521 — kept a factor of two that cancels in the correct rearrangement.
  • 5.7130 — dropped that same factor in the other direction.
  • 12.5687 — rounded an intermediate value before the final step.

Reference: FE Handbook — Specific Gravity for a Solids Slurry

Example 3
Specific Gravity for a Solids Slurry — solve for specific gravity of slurry (case 2) — Specific Gravity for a Solids Slurry (3)

slurry specific gravity from percent solids and solids specific gravity Given fraction solids by weight (W_s) = 0.0770; specific gravity of solids (S_s) = 1.2400; specific gravity of water (S_w) = 0.9930, determine the specific gravity of slurry (SG_s).

Given

  • fractionsolidsbyweight(Ws)=0.0770fraction solids by weight (W_s) = 0.0770
  • specificgravityofsolids(Ss)=1.2400specific gravity of solids (S_s) = 1.2400
  • specificgravityofwater(Sw)=0.9930specific gravity of water (S_w) = 0.9930

Find

specific gravity of slurry (SG_s)

Start with the thinking

  • The governing relation printed in this handbook section is Specific Gravity for a Solids Slurry.
  • Everything except SG_s is given, so isolate SG_s symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Specific gravity for a solids slurry combines the specific gravities of solids and water weighted by solids fraction.

Step-by-step solution

  1. Step 1 — State the governing relation:

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}
  2. Step 2 — Rearrange symbolically for SG_s:

    SGs=1WsSs+1−WsSwSG_{s} = \dfrac{1}{\dfrac{W_s}{S_s}+\dfrac{1-W_s}{S_w}}
  3. Step 3 — List the givens: fraction solids by weight (W_s) = 0.0770, specific gravity of solids (S_s) = 1.2400, specific gravity of water (S_w) = 0.9930.

  4. Step 4 — Substitute the given values:

    SGs=1WsSs+1−WsSwSG_{s} = \dfrac{1}{\dfrac{W_s}{S_s}+\dfrac{1-W_s}{S_w}}
  5. Step 5 — Evaluate:

    SGs=1.0085SG_{s} = 1.0085
  6. Step 6 — Check: returning SG_s = 1.0085 to

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}

    reproduces the given quantities, and both sides carry the same units.

Answer:
SGs=1.0085SG_{s} = 1.0085

Why the other options are there

  • 2.0169 — kept a factor of two that cancels in the correct rearrangement.
  • 0.5042 — dropped that same factor in the other direction.
  • 1.1093 — rounded an intermediate value before the final step.

Reference: FE Handbook — Specific Gravity for a Solids Slurry

Example 4
Specific Gravity for a Solids Slurry — solve for specific gravity of solids (case 2) — Specific Gravity for a Solids Slurry (4)

specific gravity for a solids slurry of sludge and water Given fraction solids by weight (W_s) = 0.2820; specific gravity of water (S_w) = 1.0100; specific gravity of slurry (SG_s) = 1.2440, determine the specific gravity of solids (S_s).

Given

  • fractionsolidsbyweight(Ws)=0.2820fraction solids by weight (W_s) = 0.2820
  • specificgravityofwater(Sw)=1.0100specific gravity of water (S_w) = 1.0100
  • specificgravityofslurry(SGs)=1.2440specific gravity of slurry (SG_s) = 1.2440

Find

specific gravity of solids (S_s)

Start with the thinking

  • The governing relation printed in this handbook section is Specific Gravity for a Solids Slurry.
  • Everything except S_s is given, so isolate S_s symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Specific gravity for a solids slurry combines the specific gravities of solids and water weighted by solids fraction.

Step-by-step solution

  1. Step 1 — State the governing relation:

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}
  2. Step 2 — Rearrange symbolically for S_s:

    Ss=Ws1SGs−1−WsSwS_{s} = \dfrac{W_s}{\dfrac{1}{SG_s}-\dfrac{1-W_s}{S_w}}
  3. Step 3 — List the givens: fraction solids by weight (W_s) = 0.2820, specific gravity of water (S_w) = 1.0100, specific gravity of slurry (SG_s) = 1.2440.

  4. Step 4 — Substitute the given values:

    Ss=Ws1SGs−1−WsSwS_{s} = \dfrac{W_s}{\dfrac{1}{SG_s}-\dfrac{1-W_s}{S_w}}
  5. Step 5 — Evaluate:

    Ss=3.0333S_{s} = 3.0333
  6. Step 6 — Check: returning S_s = 3.0333 to

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Ss=3.0333S_{s} = 3.0333

Why the other options are there

  • 6.0666 — kept a factor of two that cancels in the correct rearrangement.
  • 1.5167 — dropped that same factor in the other direction.
  • 3.3367 — rounded an intermediate value before the final step.

Reference: FE Handbook — Specific Gravity for a Solids Slurry

Example 5
Specific Gravity for a Solids Slurry — solve for specific gravity of slurry (case 3) — Specific Gravity for a Solids Slurry (5)

specific gravity calculation for a solids slurry from a thickener Given fraction solids by weight (W_s) = 0.0840; specific gravity of solids (S_s) = 1.6100; specific gravity of water (S_w) = 0.9910, determine the specific gravity of slurry (SG_s).

Given

  • fractionsolidsbyweight(Ws)=0.0840fraction solids by weight (W_s) = 0.0840
  • specificgravityofsolids(Ss)=1.6100specific gravity of solids (S_s) = 1.6100
  • specificgravityofwater(Sw)=0.9910specific gravity of water (S_w) = 0.9910

Find

specific gravity of slurry (SG_s)

Start with the thinking

  • The governing relation printed in this handbook section is Specific Gravity for a Solids Slurry.
  • Everything except SG_s is given, so isolate SG_s symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Specific gravity for a solids slurry combines the specific gravities of solids and water weighted by solids fraction.

Step-by-step solution

  1. Step 1 — State the governing relation:

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}
  2. Step 2 — Rearrange symbolically for SG_s:

    SGs=1WsSs+1−WsSwSG_{s} = \dfrac{1}{\dfrac{W_s}{S_s}+\dfrac{1-W_s}{S_w}}
  3. Step 3 — List the givens: fraction solids by weight (W_s) = 0.0840, specific gravity of solids (S_s) = 1.6100, specific gravity of water (S_w) = 0.9910.

  4. Step 4 — Substitute the given values:

    SGs=1WsSs+1−WsSwSG_{s} = \dfrac{1}{\dfrac{W_s}{S_s}+\dfrac{1-W_s}{S_w}}
  5. Step 5 — Evaluate:

    SGs=1.0241SG_{s} = 1.0241
  6. Step 6 — Check: returning SG_s = 1.0241 to

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}

    reproduces the given quantities, and both sides carry the same units.

Answer:
SGs=1.0241SG_{s} = 1.0241

Why the other options are there

  • 2.0481 — kept a factor of two that cancels in the correct rearrangement.
  • 0.5120 — dropped that same factor in the other direction.
  • 1.1265 — rounded an intermediate value before the final step.

Reference: FE Handbook — Specific Gravity for a Solids Slurry

Example 6
Specific Gravity for a Solids Slurry — solve for specific gravity of solids (case 3) — Specific Gravity for a Solids Slurry (6)

slurry specific gravity from percent solids and solids specific gravity Given fraction solids by weight (W_s) = 0.2730; specific gravity of water (S_w) = 0.9910; specific gravity of slurry (SG_s) = 1.1710, determine the specific gravity of solids (S_s).

Given

  • fractionsolidsbyweight(Ws)=0.2730fraction solids by weight (W_s) = 0.2730
  • specificgravityofwater(Sw)=0.9910specific gravity of water (S_w) = 0.9910
  • specificgravityofslurry(SGs)=1.1710specific gravity of slurry (SG_s) = 1.1710

Find

specific gravity of solids (S_s)

Start with the thinking

  • The governing relation printed in this handbook section is Specific Gravity for a Solids Slurry.
  • Everything except S_s is given, so isolate S_s symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Specific gravity for a solids slurry combines the specific gravities of solids and water weighted by solids fraction.

Step-by-step solution

  1. Step 1 — State the governing relation:

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}
  2. Step 2 — Rearrange symbolically for S_s:

    Ss=Ws1SGs−1−WsSwS_{s} = \dfrac{W_s}{\dfrac{1}{SG_s}-\dfrac{1-W_s}{S_w}}
  3. Step 3 — List the givens: fraction solids by weight (W_s) = 0.2730, specific gravity of water (S_w) = 0.9910, specific gravity of slurry (SG_s) = 1.1710.

  4. Step 4 — Substitute the given values:

    Ss=Ws1SGs−1−WsSwS_{s} = \dfrac{W_s}{\dfrac{1}{SG_s}-\dfrac{1-W_s}{S_w}}
  5. Step 5 — Evaluate:

    Ss=2.2680S_{s} = 2.2680
  6. Step 6 — Check: returning S_s = 2.2680 to

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Ss=2.2680S_{s} = 2.2680

Why the other options are there

  • 4.5361 — kept a factor of two that cancels in the correct rearrangement.
  • 1.1340 — dropped that same factor in the other direction.
  • 2.4948 — rounded an intermediate value before the final step.

Reference: FE Handbook — Specific Gravity for a Solids Slurry

Example 7
Specific Gravity for a Solids Slurry — solve for specific gravity of slurry (case 4) — Specific Gravity for a Solids Slurry (7)

specific gravity for a solids slurry of sludge and water Given fraction solids by weight (W_s) = 0.1830; specific gravity of solids (S_s) = 1.4900; specific gravity of water (S_w) = 1.0050, determine the specific gravity of slurry (SG_s).

Given

  • fractionsolidsbyweight(Ws)=0.1830fraction solids by weight (W_s) = 0.1830
  • specificgravityofsolids(Ss)=1.4900specific gravity of solids (S_s) = 1.4900
  • specificgravityofwater(Sw)=1.0050specific gravity of water (S_w) = 1.0050

Find

specific gravity of slurry (SG_s)

Start with the thinking

  • The governing relation printed in this handbook section is Specific Gravity for a Solids Slurry.
  • Everything except SG_s is given, so isolate SG_s symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Specific gravity for a solids slurry combines the specific gravities of solids and water weighted by solids fraction.

Step-by-step solution

  1. Step 1 — State the governing relation:

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}
  2. Step 2 — Rearrange symbolically for SG_s:

    SGs=1WsSs+1−WsSwSG_{s} = \dfrac{1}{\dfrac{W_s}{S_s}+\dfrac{1-W_s}{S_w}}
  3. Step 3 — List the givens: fraction solids by weight (W_s) = 0.1830, specific gravity of solids (S_s) = 1.4900, specific gravity of water (S_w) = 1.0050.

  4. Step 4 — Substitute the given values:

    SGs=1WsSs+1−WsSwSG_{s} = \dfrac{1}{\dfrac{W_s}{S_s}+\dfrac{1-W_s}{S_w}}
  5. Step 5 — Evaluate:

    SGs=1.0687SG_{s} = 1.0687
  6. Step 6 — Check: returning SG_s = 1.0687 to

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}

    reproduces the given quantities, and both sides carry the same units.

Answer:
SGs=1.0687SG_{s} = 1.0687

Why the other options are there

  • 2.1373 — kept a factor of two that cancels in the correct rearrangement.
  • 0.5343 — dropped that same factor in the other direction.
  • 1.1755 — rounded an intermediate value before the final step.

Reference: FE Handbook — Specific Gravity for a Solids Slurry

Example 8
Specific Gravity for a Solids Slurry — solve for specific gravity of solids (case 4) — Specific Gravity for a Solids Slurry (8)

specific gravity calculation for a solids slurry from a thickener Given fraction solids by weight (W_s) = 0.2950; specific gravity of water (S_w) = 0.9970; specific gravity of slurry (SG_s) = 1.2370, determine the specific gravity of solids (S_s).

Given

  • fractionsolidsbyweight(Ws)=0.2950fraction solids by weight (W_s) = 0.2950
  • specificgravityofwater(Sw)=0.9970specific gravity of water (S_w) = 0.9970
  • specificgravityofslurry(SGs)=1.2370specific gravity of slurry (SG_s) = 1.2370

Find

specific gravity of solids (S_s)

Start with the thinking

  • The governing relation printed in this handbook section is Specific Gravity for a Solids Slurry.
  • Everything except S_s is given, so isolate S_s symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Specific gravity for a solids slurry combines the specific gravities of solids and water weighted by solids fraction.

Step-by-step solution

  1. Step 1 — State the governing relation:

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}
  2. Step 2 — Rearrange symbolically for S_s:

    Ss=Ws1SGs−1−WsSwS_{s} = \dfrac{W_s}{\dfrac{1}{SG_s}-\dfrac{1-W_s}{S_w}}
  3. Step 3 — List the givens: fraction solids by weight (W_s) = 0.2950, specific gravity of water (S_w) = 0.9970, specific gravity of slurry (SG_s) = 1.2370.

  4. Step 4 — Substitute the given values:

    Ss=Ws1SGs−1−WsSwS_{s} = \dfrac{W_s}{\dfrac{1}{SG_s}-\dfrac{1-W_s}{S_w}}
  5. Step 5 — Evaluate:

    Ss=2.9125S_{s} = 2.9125
  6. Step 6 — Check: returning S_s = 2.9125 to

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Ss=2.9125S_{s} = 2.9125

Why the other options are there

  • 5.8251 — kept a factor of two that cancels in the correct rearrangement.
  • 1.4563 — dropped that same factor in the other direction.
  • 3.2038 — rounded an intermediate value before the final step.

Reference: FE Handbook — Specific Gravity for a Solids Slurry

Example 9
Specific Gravity for a Solids Slurry — solve for specific gravity of slurry (case 5) — Specific Gravity for a Solids Slurry (9)

slurry specific gravity from percent solids and solids specific gravity Given fraction solids by weight (W_s) = 0.1420; specific gravity of solids (S_s) = 2.4200; specific gravity of water (S_w) = 1.0080, determine the specific gravity of slurry (SG_s).

Given

  • fractionsolidsbyweight(Ws)=0.1420fraction solids by weight (W_s) = 0.1420
  • specificgravityofsolids(Ss)=2.4200specific gravity of solids (S_s) = 2.4200
  • specificgravityofwater(Sw)=1.0080specific gravity of water (S_w) = 1.0080

Find

specific gravity of slurry (SG_s)

Start with the thinking

  • The governing relation printed in this handbook section is Specific Gravity for a Solids Slurry.
  • Everything except SG_s is given, so isolate SG_s symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Specific gravity for a solids slurry combines the specific gravities of solids and water weighted by solids fraction.

Step-by-step solution

  1. Step 1 — State the governing relation:

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}
  2. Step 2 — Rearrange symbolically for SG_s:

    SGs=1WsSs+1−WsSwSG_{s} = \dfrac{1}{\dfrac{W_s}{S_s}+\dfrac{1-W_s}{S_w}}
  3. Step 3 — List the givens: fraction solids by weight (W_s) = 0.1420, specific gravity of solids (S_s) = 2.4200, specific gravity of water (S_w) = 1.0080.

  4. Step 4 — Substitute the given values:

    SGs=1WsSs+1−WsSwSG_{s} = \dfrac{1}{\dfrac{W_s}{S_s}+\dfrac{1-W_s}{S_w}}
  5. Step 5 — Evaluate:

    SGs=1.0991SG_{s} = 1.0991
  6. Step 6 — Check: returning SG_s = 1.0991 to

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}

    reproduces the given quantities, and both sides carry the same units.

Answer:
SGs=1.0991SG_{s} = 1.0991

Why the other options are there

  • 2.1981 — kept a factor of two that cancels in the correct rearrangement.
  • 0.5495 — dropped that same factor in the other direction.
  • 1.2090 — rounded an intermediate value before the final step.

Reference: FE Handbook — Specific Gravity for a Solids Slurry

Example 10
Specific Gravity for a Solids Slurry — solve for specific gravity of solids (case 5) — Specific Gravity for a Solids Slurry (10)

specific gravity for a solids slurry of sludge and water Given fraction solids by weight (W_s) = 0.1270; specific gravity of water (S_w) = 1.0100; specific gravity of slurry (SG_s) = 1.0790, determine the specific gravity of solids (S_s).

Given

  • fractionsolidsbyweight(Ws)=0.1270fraction solids by weight (W_s) = 0.1270
  • specificgravityofwater(Sw)=1.0100specific gravity of water (S_w) = 1.0100
  • specificgravityofslurry(SGs)=1.0790specific gravity of slurry (SG_s) = 1.0790

Find

specific gravity of solids (S_s)

Start with the thinking

  • The governing relation printed in this handbook section is Specific Gravity for a Solids Slurry.
  • Everything except S_s is given, so isolate S_s symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Specific gravity for a solids slurry combines the specific gravities of solids and water weighted by solids fraction.

Step-by-step solution

  1. Step 1 — State the governing relation:

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}
  2. Step 2 — Rearrange symbolically for S_s:

    Ss=Ws1SGs−1−WsSwS_{s} = \dfrac{W_s}{\dfrac{1}{SG_s}-\dfrac{1-W_s}{S_w}}
  3. Step 3 — List the givens: fraction solids by weight (W_s) = 0.1270, specific gravity of water (S_w) = 1.0100, specific gravity of slurry (SG_s) = 1.0790.

  4. Step 4 — Substitute the given values:

    Ss=Ws1SGs−1−WsSwS_{s} = \dfrac{W_s}{\dfrac{1}{SG_s}-\dfrac{1-W_s}{S_w}}
  5. Step 5 — Evaluate:

    Ss=2.0344S_{s} = 2.0344
  6. Step 6 — Check: returning S_s = 2.0344 to

    1SGs=WsSs+WwSw\dfrac{1}{SG_s} = \dfrac{W_s}{S_s} + \dfrac{W_w}{S_w}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Ss=2.0344S_{s} = 2.0344

Why the other options are there

  • 4.0687 — kept a factor of two that cancels in the correct rearrangement.
  • 1.0172 — dropped that same factor in the other direction.
  • 2.2378 — rounded an intermediate value before the final step.

Reference: FE Handbook — Specific Gravity for a Solids Slurry

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