Question

An object that is thrown straight up falls back to Earth. This is one-dimensional motion.

(a) When is its velocity zero?

(b) Does its velocity change direction?

(c) Does the acceleration due to gravity have the same sign on the way up as on the way down?

Short answer

a)The velocity is zero when the object reaches the peak distance.

b)Yes, there is a change in velocity direction.

c) The acceleration owing to gravitation does not have the same sign on the way up and down.

Step-by-step solution

Step 1: When is its velocity zero?

a)

As the object moves up higher in altitude, its velocity diminishes until it reaches zero at the highest point.

The velocity of the item rises as it descends, reaching its maximum just before it reaches the earth.

Direction of velocity

b)

The object's velocity is always oriented in the direction of the object's motion.

When an object goes upward, the object's direction is upward, and when it moves below, the object's direction is downward.

As a result, the object's velocity switches direction.

When the object moves upward, velocity is also upward.

When the object is moving downward, velocity also directs downward.

Direction of acceleration

c)

The upward movement of the item is in the opposite direction of gravity acceleration, and the sign of gravity acceleration becomes negative.

The item will go downhill in the same direction as the acceleration caused by gravity. Gravitational acceleration has apositive sign.

As a result, the acceleration owing to gravitation does not have the same sign on the way up and down.

Hence the velocity is zero at maximum height, and the velocity will change its direction in the above case, and acceleration will also change its direction.