Question

Use this information to answer the next 2 questions: a 0.32 kg ball is thrown with a speed of 11.5 m/s. 18. how much kinetic energy does the ball have? 42.3 j 1.84 j 35.9 j 21.2 j 19. how much work would be needed to stop the ball?

Answer 1

Given:

m = 0.32 kg

v = 11.5 m/s

To find:

1) Kinetic energy = ?

2) Work needed to stop the ball = ?

Formula used:

1) Kinetic energy =
`(1)/(2) m v^(2)`

2) Work = kinetic energy

Solution:

1)

Kinetic energy is given by,

Kinetic energy =
`(1)/(2) m v^(2)`

K.E. =
`(1)/(2) 0.32 * 11.5 * 11.5`

K.E. = 21.16 Joule

Thus, option (d) is the correct answer.

2)

Work needed to stop the ball is same as the kinetic energy because energy is the capacity to do work. Since, work is opposing the movement of the ball. Thus, Work = - Kinetic energy

Work = -21.16 Joule