Question

A couple of soccer balls of equal mass are kicked off the ground at the same speed, butat different angles. Soccer ball A is kicked off at an angle slightly above the horizontal,whereas ball B is kicked slightly below the vertical.(a) How does the initial kinetic energy of ball A compare to the initial kinetic energyof ball B?(b) How does the change in gravitational potential energy from the ground to thehighest point for ball A compare to the change in gravitational potential energyfrom the ground to the highest point for ball B?(c) If the energy in part (a) di ers from the energy in part (b), explain why there is adi erence between the two energies.

Answer 1

Answer:

Remember that Kinetic energy is a scalar quantity and it only depends on the speed and not necessary not the angle

Thus,Since the masses and the speed are same for both A and B, the initial kinetic energy of A and B are same.

b]

The difference or variation in gravitational potential energy is again a scalar quantity and so as long as the initial speed is same, the change in gravitational potential energy will also be the same [though they may not occur at the same horizontal position].

therefore, from the ground to the highest point of both A and B, both will have same potential energy.

Also The energy in part (a) differs from part (b),

In part (a) energy mention is kinetic energy that depends on mass and velocity of particle whereas in part (b) energy is potential energy that depends on mass and the position with reference of ground. Potential energy is a state function but kinetic energy is not.