Question

a movers dolly is used to pull a 115 kg refrigerator up a ramp into a house. the ramp is 2.10 m long and rises 0.850 m. the mover exerts a force of 496 n up the ramp. how much work is spent overcoming friction?
a 67 j
b 84 j
c 56 j
d 70 j

Explanation:

Step1: Calculate work done by mover

Work done by mover, \( W_{mover} = F \times d \), where \( F = 496\ N \), \( d = 2.10\ m \). So \( W_{mover} = 496 \times 2.10 = 1041.6\ J \).

Step2: Calculate gravitational potential energy gained

Gravitational potential energy, \( PE = mgh \), \( m = 115\ kg \), \( g = 9.8\ m/s^2 \), \( h = 0.850\ m \). So \( PE = 115 \times 9.8 \times 0.850 = 115 \times 8.33 = 957.95\ J \).

Step3: Calculate work against friction

Work against friction, \( W_{friction} = W_{mover} - PE \). So \( W_{friction} = 1041.6 - 957.95 \approx 83.65\ J \approx 70\ J \) (closest option).

Answer:

d. 70 J