Question

identifying balanced and unbalanced forces
identify the situations that have an unbalanced force. choose three correct answers.
□ a hockey puck
moves in a straight
line at a constant
speed
□ a balloon flies
across the room
when the air is
released
□ a weight speeds
up as it falls
through the air
□ a garbage can is at
rest on the ground
□ a bumper car hit
by another car
moves off at an
angle

Explanation:

To determine unbalanced forces, we use Newton's laws: unbalanced forces cause a change in motion (speed or direction).

• A hockey puck moving at constant speed in a straight line has balanced forces (no change in motion).
• A balloon flying across the room: its motion changes (starts moving), so unbalanced forces.
• A weight speeding up as it falls: speed changes, so unbalanced forces (gravity > air resistance).
• A garbage can at rest: balanced forces (net force = 0).
• A bumper car hit and moving off at an angle: direction changes, so unbalanced forces.

So the three situations with unbalanced forces are the balloon flying, the weight speeding up, and the bumper car moving off at an angle.

Answer:

• A balloon flies across the room when the air is released
• A weight speeds up as it falls through the air
• A bumper car hit by another car moves off at an angle