A labour has to throw bricks near mistry 16 feet vertically above. He throws the bricks in such a manner that the brick reach the mistry with the velocity of 16ft/sec. If he throws bricks such that bricks just reach the mistry, then the portion of the energy saved is ?
The options are (a) 1/3 (b) 1/4 (c) 1/5 (d) 1/6
The values which i circled in my answer are wrong
So what is the correct explanation which matches my option
The one who tells that I will mark him brainliest
Answers
portion of the energy saved is 1/5
Explanation:
a = -g
using V² - U² = 2aS
=> 16² - U² = 2(-g)(16)
=> U² = 16² + 2(g)(16)
Energy required = (1/2)mU² = (1/2)m(16² + 2(g)(16))
using g = 32
= (1/2)m(16² + 2(32)(16))
= (1/2)m(16)²(1 + 4)
= (1/2)m(16)²(5)
using V² - U² = 2aS
=> 0² - U² = 2(-g)(16)
=> U² = 2(g)(16)
Energy required = (1/2)mU² = (1/2)m(2(32)(16))
= (1/2)m(16)²(4)
Energy Saved = ((1/2)m(16)²(5) - (1/2)m(16)²(4))/ (1/2)m(16)²(5)
= (1/2)m(16)²(1)/ (1/2)m(16)²(5)
= 1/5
1/5 is the Correct option c
Another way
Energy at top = mgh + (1/2)mv² = m(32)(16) + (1/2)m16² = (1/2)m(16)²(5)
& Energy at top = mgh = m(32)(16) = (1/2)m(16)²(4)
Learn more:
what happens to the kinetic energy when: (A)the mass of the body is ...
https://brainly.in/question/7486455
two toy cars A and B of masses 200g and 500g respectively are ...
https://brainly.in/question/7342101