Work Energy And Power Question 205

Question: A ball whose kinetic energy is E, is projected at an angle of 45 to the horizontal. The kinetic energy of the ball at the highest point of its flight will be

Options:

A) E

B) E/2

C) E/2

D) zero

Show Answer

Answer:

Correct Answer: C

Solution:

[c] Let u be the speed with which the ball of mass m is projected.

Then the kinetic energy (E) at the point of projection is E=12mu2 -(i)

When the ball is at the highest point of its flight, the speed of the ball is u2 (Remember that the horizontal component of velocity does not change during a projectile motion).
The kinetic energy at the highest point =12m(u2)2=12mu22=E2 [From (i)]



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