Question

A projectile is fired at an angle above the level ground. Where does it have maximum kinetic energy? Is it right when it leaves the launcher and right before it hits the ground?

Answer 1

It has maximum kinetic energy at the starting of projectile and the end of projectile.

Step-by-step explanation:

If a projectile is projected at some angle to the horizontal then have maximum kinetic energy at the starting of projectile and the end of projectile. Since Ke=1/2*mv² and here the velocity is the resultant of two velocities at horizontal direction and vertical direction which is given by the parallelogram law of vector. With the passage of time due to the resistance of air friction its speed is reduced and when it again comes to the ground the speed increases due to gravitational pull.

Answer 2

You can approach this problem in an analytical way. The formula for kinetic energy is 1/2*mv². Throughout the projectile motion, mass is constant. Therefore, it wholly depends on the velocity. So, the maximum kinetic energy is when the object travels the fastest. This is right when it leaves the launcher, and the moment just before it hits the ground.