Work,Energy and Power

  • Thread starter alijan kk
  • Start date
  • #1
130
5

Homework Statement


A body of mass 2 kg thrown vertically with KE of 490 joules. If the acceleration due to gravity is 9.8 m/s^2 of the body becomes half its original value is given by:

a.50
b.12.5
c.25 m
d.10 m

Homework Equations


PE=MGH
K.E=1/2MV^2
PE=KE

The Attempt at a Solution



K.E=P.E
490=MGH
490=2*9.8*H
490=19.6*H
490/19.6=H
25=H
H=25 m

is it right ? or we have to half the value.
 

Answers and Replies

  • #2
jbriggs444
Science Advisor
Homework Helper
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What is the question? The second sentence is incoherent. My best guess is that it is asking how high the body needs to go to lose half of its kinetic energy due to gravity.

In that case, the Kinetic Energy that is lost and the Potential Energy that is gained are both half of 490 joules.
 
  • #3
130
5
yes sorry the sentence is . "the height at which the K.E of the body becomes half its original value is given by"
 

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