Question

1. a weightlifter holds a 150 kg barbell above their head for 10 seconds. the barbell remains stationary. how much work did the weightlifter do on the barbell?

Explanation:

Step1: Recall work - formula

The work formula is $W = F\times d\times\cos\theta$, where $W$ is work, $F$ is force, $d$ is displacement, and $\theta$ is the angle between the force and the displacement.

Step2: Analyze the situation

The weightlifter holds the barbell stationary. So, the displacement $d = 0$ m.

Step3: Calculate work

Substitute $d = 0$ into the work - formula: $W=F\times0\times\cos\theta = 0$ J.

Answer:

0 J