Question

From the edge of a roof you throw a snowball downward that strikes the ground with 100J of kinetic energy. then you throw a second snowball upward with the same initial speed, and this too falls to the ground. neglecting air resistance, the second snowball hits the ground with a kinetic energy of:
a. 100J
b. 200J
c. more than 200J
d. less than 200J
e. none of the above

Answer 1

Answer:

The second snowball hits the ground with a kinetic energy of 100 Joules

Explanation:

Given that,

From the edge of a roof you throw a snowball downward that strikes the ground with 100 J of kinetic energy. It is a case of conservation of energy.

At the highest point,

$mgh+\dfrac{1}{2}mu^2=mgh'+0$          

$100=mgh'$

At lowest point,

$mgh'=K$

From above two equation, we get :

Kinetic energy, K = 100 J

So, the second snowball hits the ground with a kinetic energy of 100 Joules. So, the correct option is (A).