Which situations are examples of a particle with a non-zero acceleration? (Select all that are true for full credit.)
a)A car driving around a circular track at constant speed.
b)A child going back and forth on a swing
c)A runner moving in a straight line with a constant speed.
d)A car driving in a straight line and coming to a stop at a stop sign.
a, and c.
To determine which situations represent a particle with a non-zero acceleration, we need to understand what acceleration refers to. Acceleration is defined as the rate at which the velocity of an object changes with time. In simpler terms, it measures how quickly the speed or direction of an object changes.
a) A car driving around a circular track at a constant speed: In this case, although the car is moving in a circle, the speed remains constant. Since acceleration measures changes in velocity, and velocity involves both speed and direction, the car's velocity remains the same throughout the circular motion. Therefore, the acceleration in this situation is zero. So option a) does not represent a particle with non-zero acceleration.
b) A child going back and forth on a swing: As the child swings back and forth, the direction and speed continuously change. The swinging motion results in a non-zero acceleration because the velocity is constantly changing. Therefore, option b) represents a particle with non-zero acceleration.
c) A runner moving in a straight line with a constant speed: When a runner moves in a straight line with a constant speed, there is no change in velocity. Since acceleration measures changes in velocity, and no changes are occurring, the acceleration in this situation is zero. Therefore, option c) does not represent a particle with non-zero acceleration.
d) A car driving in a straight line and coming to a stop at a stop sign: When a car is moving in a straight line and comes to a stop, its velocity decreases from a non-zero value to zero. As there is a change in velocity, this situation represents a non-zero acceleration. Therefore, option d) represents a particle with non-zero acceleration.
In summary, the situations that represent a particle with a non-zero acceleration are:
- b) A child going back and forth on a swing
- d) A car driving in a straight line and coming to a stop at a stop sign.