Question

A ball is launched from ground level and hits the ground again after an elapsed time of 4 seconds and after traveling a horizontal distance of 56 m. The only force acting on the ball is gravity. Which of the following statements best describes the magnitude of the horizontal component of the velocity of the ball? a. It is constant the whole time the ball is in free-fall. b. It is smallest when the height of the ball is maximum. c. It is smallest just before the ball hits the ground. What is the initial x-component of the ball's velocity? a. = 17.1 m/s b. = 14 m/s c. = 20.2 m/s d. = 10.8 m/s e. = 23.2 m/s What is the initial y-component of the ball's velocity? a. = 32.6 m/s b. = 26.1 m/

Answer 1

Answer:

1)a. It is constant the whole time the ball is in free-fall.

2)b. = 14 m/s

3) e. = 19.6 m/s

Explanation:

1) given that the only force acting on the ball is gravity, gravity acts along the vertical axis. Since no other force acts on the ball then the horizontal velocity will remain constant all through the flight since there is no horizontal force acting on the ball.

2) speed = distance/time

horizontal distance = 56m

Time = 4 seconds

Speed = 56m/4s = 14m/s

3) acceleration due to gravity g = 9.8m/s^2

Initial vertical velocity = u

Final vertical velocity = v = -u

Using the law of motion;

v = u + at

a = acceleration = -g = -9.8m/s^2

t = time of flight = 4

Substituting the values;

-u = u - 4(9.8)

-2u = -4(9.8)

u = -4(9.8)/-2

u = 2(9.8) = 19.6 m/s

Initial vertical velocity = u = 19.6 m/s