Chat with tutor

Ask Questions, Get Answers


A man throws the brick to a height of 12 m with a speed of 12 m/s. If he throws the brick in such a way that they just reach that height , what percentage of energy will be saved

\[(a)\;29\;\% \quad (b)\;38\;\% \quad (c)\;46\;\% \quad (d)\;50\;\%\]

1 Answer

When the brick reaches 12 m height when thrown  with velocity 12 m/s it has both potential energy and kinetic energy
When it just reaches the same height, it has only Potential energy, as its velocity is zero at its maximum height.
Therefore $ \%$ of energy saved $=\large\frac{KE}{KE+PE}$$\times 100$
$\qquad= \large\frac{\Large\frac{1}{2}mv^2}{\Large\frac{1}{2}mv^2+mgh} $$\times 100$
$\qquad=\large\frac{12^2}{12^2+2 \times 9.8 \times 12}$$ \times 100$
$\qquad=38 \%$
Hence  b is the correct answer.


Help Clay6 to be free
Clay6 needs your help to survive. We have roughly 7 lakh students visiting us monthly. We want to keep our services free and improve with prompt help and advanced solutions by adding more teachers and infrastructure.

A small donation from you will help us reach that goal faster. Talk to your parents, teachers and school and spread the word about clay6. You can pay online or send a cheque.

Thanks for your support.
Please choose your payment mode to continue
Home Ask Homework Questions
Your payment for is successful.
Clay6 tutors use Telegram* chat app to help students with their questions and doubts.
Do you have the Telegram chat app installed?
Already installed Install now
*Telegram is a chat app like WhatsApp / Facebook Messenger / Skype.