Question

which of the following are examples of unbalanced forces acting on an object? rolling a bowling ball a bird flying at constant speed and direction jumping off a diving board opening the microwave door a person standing still in line

Explanation:

Step1: Recall force - balance concept

Balanced forces keep an object at rest or in constant motion. Unbalanced forces cause a change in motion.

Step2: Analyze rolling a bowling ball

A force is applied to start it moving and friction acts against it, changing its motion - unbalanced forces.

Step3: Analyze bird flying at constant speed

The forces (lift, drag, thrust, weight) are balanced as it has constant speed and direction.

Step4: Analyze jumping off a diving board

The jumper's body accelerates downwards due to gravity and the force from the jump - unbalanced forces.

Step5: Analyze opening the microwave door

A force is applied to change the door's state from rest to motion - unbalanced forces.

Step6: Analyze person standing still

The person's weight is balanced by the normal force from the ground - balanced forces.

Answer:

rolling a bowling ball, jumping off a diving board, opening the microwave door