select all the correct answers. in which situations is work being done? hannah leans against her locker, but…

Explanation:

Step1: Recall work - done 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. For work to be done, there must be a non - zero displacement in the direction of the force.

Step2: Analyze Hannah's situation

Hannah leans against the locker. Force is applied but displacement (d = 0). So, (W=0) (no work done).

Step3: Analyze Andy's car situation

Andy's car rolls down a hill. There is a gravitational force acting on the car and the car has a displacement in the direction of the gravitational force component along the slope of the hill. So, work is done by gravity on the car.

Step4: Analyze wind - turbine situation

The wind turbine is still. There is no force causing a displacement. So, (W = 0) (no work done).

Step5: Analyze balloon situation

The balloon expands due to the heat from the Sun. There is a force (pressure force) causing a displacement (expansion). So, work is done.

Step6: Analyze James' situation

James pedals a stationary exercise cycle. Although he applies a force, the cycle doesn't move (displacement (d = 0)). So, (W=0) (no work done).

Answer:

Andy's car rolls down a hill with the engine off; A balloon expands as it is heated by the Sun.