Question

A ball is thrown upward. At a height of 10 meters above the ground, the ball has a potential energy of 50 joules (with the potential energy equal to zero at ground level) and is moving upward with a kinetic energy of 50 joules. Air friction is negligible. The maximum height reached by the ball is most nearly

Answer 1

The maximum height reached by the ball is most nearly 20 metres

• The solution follows from the law of conservation of energy

• According to it, the sum of potential energy and kinetic energy always remains the same.

• Potential energy is 0 at surface and maximum at top while

• Kinetic energy is maximum at surface and 0 at top.

• According to the question,

PE= mgh = 50 J -(1)

mg* 10 = 50

mg = 5 units

• Total energy at that point = PE + KE = 100 J

• So at topmost point , PE will be 100 J

• mgH = 100J , H is the required height

• Using the value of mg obtained above, we have

H= 100/5

H = 20 m

Answer 2

Answer:

7 joules and 20 meters

Explanation: