Uniform Circular Motion

𝒂_𝒄 = 𝒗²/r

The magnitude of the centripetal acceleration, 𝑎𝑐 , in relation with the angular velocity 𝑣 and radius of the circular path 𝑟, is given by

1. A ball is thrown with an initial horizontal velocity of 10 𝑚/𝑠. If it is initially 44.1 m from the ground, how long does it take before the ball hits the ground?

a. 2 s

b. 3 s

c. 4 s

d. 5 s

a. 0 m/s

NOTE:

• 𝑣𝑦 = 0 𝑚/s²

2. A car rides off the edge of a cliff. Just at the edge, its velocity is horizontal, with a magnitude of 100 m/s. What is the initial downward velocity of the car?

a. 0 m/s

b. 50 m/s

c. 100 m/s

d. cannot be determined

a. 0.00 m/s2

NOTE:

• 𝑎𝑥 = 0 𝑚/𝑠²

3. Jaja shoots a projectile from a gun making an angle of 450 with the horizontal. The initial velocity of the bullet is 100 m/s. Assume that g = 10 m/s2 . After 5 seconds, what is the bullet’s acceleration along the x-axis?

a. 0.00 m/s2

c. 96.6 m/s2

b. 10.0 m/s2

d. 100.00 m/s2

b. It has a constant speed and a changing velocity.

4. A car moves in a clockwise direction in a circular track. It moves with a velocity of 10 m/s all throughout its course. Which of the following is true about the speed and velocity of the car?

a. It has a changing speed and a constant velocity.

b. It has a constant speed and a changing velocity.

c. It has a constant speed and a constant velocity.

d. Both the speed and the velocity are changing

a.(↑)

Use the diagram below to answer the question that follows.

The diagram above represents a Ferris wheel rotating at a constant speed. Which of the following vectors represents the acceleration of a person on the wheel at point Y?

a.(↑)

b. (→)

C. (↓)

d.(↗)