A boy throws a ball vertically upwards with a velocity of 10m/s.What is the velocity of the ball when it is half way up?

Half of its original kinetic energy is gone

final KE=1/2 orig KE
1/2 m v'^2=1/4 m vi^2

v'= vi = sqrt(1/2)=.707 vi

To find out the velocity of the ball when it is halfway up, we need to understand the basic principles of projectile motion.

When a ball is thrown vertically upwards, it experiences a constant acceleration due to gravity that acts in the opposite direction of the initial velocity. In this case, the acceleration due to gravity is approximately 9.8 m/s² always acting downwards.

At the highest point, the ball momentarily stops and starts falling back downwards. Therefore, the velocity of the ball when it is at the halfway point will be the same magnitude as the initial velocity but in the opposite direction.

So, if the initial velocity is 10 m/s, then at the halfway point, the velocity of the ball will be -10 m/s (negative because it is in the opposite direction of the initial velocity).

Thus, the velocity of the ball when it is halfway up is -10 m/s.