Question

question 13.
which examples illustrate the impact of unbalanced forces on a bicycle?
select two answers.
a. the bicycle is coasting down a hill at a constant speed without pedaling.
b. the cyclist is pedaling harder to speed up when going uphill.
c. the bicycle is moving at a constant speed on a flat road.
d. the cyclist applies the brakes and comes to a stop.
e. the bicycle is at rest on the side of a road.

Explanation:

• For option B: When a cyclist pedals harder to speed up going uphill, the applied force (from pedaling) overcomes the opposing forces (like gravity and friction). This means there is an unbalanced force causing a change in motion (acceleration).
• For option D: When the cyclist applies brakes, the frictional force from the brakes is greater than the forward - moving force of the bicycle. This unbalanced force causes the bicycle to decelerate and come to a stop.

• For option A: If the bicycle is coasting down a hill at a constant speed without pedaling, the forces (gravity pulling down the hill and friction opposing the motion) are balanced.
• For option C: When moving at a constant speed on a flat road, the force applied (if any, like from previous pedaling) is balanced by friction.
• For option E: When at rest, the forces (gravity pulling down and normal force from the road pushing up) are balanced.

Answer:

B. The cyclist is pedaling harder to speed up when going uphill.
D. The cyclist applies the brakes and comes to a stop.