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 force \( W_{mover} = F \times d \), where \( F = 496 \, \text{N} \), \( d = 2.10 \, \text{m} \).
\( W_{mover} = 496 \times 2.10 = 1041.6 \, \text{J} \).

Step2: Calculate gravitational potential energy gain

Potential energy \( PE = mgh \), \( m = 115 \, \text{kg} \), \( g = 9.8 \, \text{m/s}^2 \), \( h = 0.850 \, \text{m} \).
\( PE = 115 \times 9.8 \times 0.850 = 115 \times 8.33 = 957.95 \, \text{J} \).

Step3: Find work against friction

Work against friction \( W_{friction} = W_{mover} - PE \).
\( W_{friction} = 1041.6 - 957.95 = 83.65 \approx 84 \, \text{J} \).

Answer:

b. 84 J