Question 127: Work, Energy and Power & Circular Motion

Question

A boy is rolling a 0.5 kg ball on the frictionless floor with the speed of 20 ms
-1
. The ball gets deflected by an obstacle on the way. After deflection it moves with 5% of its initial kinetic energy. What is the speed of the ball now?

Accepted Answer

$$K.E{._f} = 5\% \,K{E_i}$$
$${1 \over 2}m{v^2} = {5 \over {100}} 	imes {1 \over 2} 	imes m 	imes {20^2}$$
$${v^2} = {1 \over {20}} 	imes {20^2} = 20$$
$$v = \sqrt {20}  = 2\sqrt 5 $$ m/s
= 4.47 m/s

Answer

14.41 ms
$$-$$1

Answer

19.0 ms
$$-$$1

Answer

4.47 ms
$$-$$1

Answer

1.00 ms
$$-$$1

Work, Energy and Power & Circular Motion

A boy is rolling a 0.5 kg ball on the frictionless floor with the speed of 20 ms -1 . The ball gets deflected by an obstacle on the way. After deflection it moves with 5% of its initial kinetic energy. What is the speed of the ball now?

Choose the correct answer: