4 m 3 of water is to be pumped to a height of 20 m and forced into a reservoir at a pressure of 2 × 105 N / m 2. The work done by the motor is (external pressure =105 N / m 2 )

Question

4 m 3 of water is to be pumped to a height of 20 m and forced into a reservoir at a pressure of 2 × 105 N / m 2. The work done by the motor is (external pressure =105 N / m 2 ) (A)  8× 105J  (B)  16× 105 J  (C)  12× 105 J  (D)  32× 105 J

Tardigrade Admin · Accepted Answer

Work done W=m g h+Δ p V =V ρ g h+Δ p V Here, V=4 m3, ρ=103 kg / m 3, g=10 m / s 2, h=20 m, Δ p=(2 × 105-1 × 105) N / m2 ∴ W=4 × 103 × 10 × 20+(2 × 105-1 × 105) × 4 =8 × 105+4 × 105 =12 × 105 J

Q. $4 m^{3}$ of water is to be pumped to a height of $20 m$ and forced into a reservoir at a pressure of $2 \times 1 0^{5} N / m^{2}$ . The work done by the motor is (external pressure $= 1 0^{5} N / m^{2}$ )

$8 \times 10^{5} J$

$16 \times 10^{5} J$

$12 \times 10^{5} J$

$32 \times 10^{5} J$

Q. 4m3 of water is to be pumped to a height of 20m and forced into a reservoir at a pressure of 2×105N/m2. The work done by the motor is (external pressure =105N/m2 )

8×105J

16×105J

12×105J

32×105J

Work done W=mgh+ΔpV =Vρgh+ΔpV Here, V=4m3,ρ=103kg/m3,g=10m/s2, h=20m,Δp=(2×105−1×105)N/m2 ∴W=4×103×10×20+(2×105−1×105)×4 =8×105+4×105 =12×105J

Q. $4 m^{3}$ of water is to be pumped to a height of $20 m$ and forced into a reservoir at a pressure of $2 \times 1 0^{5} N / m^{2}$ . The work done by the motor is (external pressure $= 1 0^{5} N / m^{2}$ )

$8 \times 10^{5} J$

$16 \times 10^{5} J$

$12 \times 10^{5} J$

$32 \times 10^{5} J$