Question

1. which of the following objects has no work done on it? a ball that is pushed down a hill a wall that is being pushed on by a person a barbell that is lifted off the floor a wagon pulled down a sidewalk

Explanation:

Step1: Recall work - formula

Work \(W = F\times d\times\cos\theta\), where \(F\) is force, \(d\) is displacement, and \(\theta\) is the angle between force and displacement. If \(d = 0\), \(W=0\).

Step2: Analyze each option

• A ball pushed down a hill has force and displacement, so work is done.
• A wall being pushed by a person: If the wall doesn't move (\(d = 0\)), according to \(W = F\times d\times\cos\theta\), work done \(W = 0\).
• A barbell lifted off the floor has force and displacement, so work is done.
• A wagon pulled down a sidewalk has force and displacement, so work is done.

Answer:

a wall that is being pushed on by a person