Work Energy And Power Question 221
Question: Calculate the K.E and RE. of the ball half way up, when a ball of mass 0.1 kg is thrown vertically upwards with an initial speed of $ 20m{s^{-1}} $ .
Options:
A) $ 10J,20J $
B) $ 10J,10J $
C) $ 15J,8J $
D) $ 8J,16J $
Show Answer
Answer:
Correct Answer: B
Solution:
[b] Total energy at the time of projection
$ =\frac{1}{2}mv^{2}=\frac{1}{2}\times 0.1{{( 20 )}^{2}}=20J $
Half way up, P.E. becomes half the P.E. at the top i.e. $ P.E.=\frac{20}{2}=10J $
$ \therefore K.E. =20-10=10J $
