Physics
A a body is released from a height. During its motion in striking the ground, the quantity which does not change is:
- momentum
- kinetic energy
- potential energy
- mechanical energy
Answer
mechanical energy
Reason — Mechanical energy, which is the sum of kinetic and potential energy, remains constant during the motion of the body. Initially, when the body is released from a height, it has potential energy. As it falls, this potential energy decreases while its kinetic energy increases. However, the sum of kinetic and potential energy (mechanical energy) remains constant in the absence of external forces like air resistance.
Related Questions
A skater is gliding on a smooth ice surface. What happens to his mechanical energy as he skates?
- It increases
- It decreases
- It becomes zero
- It remains constant
A spring is compressed storing potential energy. When the spring is released it propels an object forward. What change would you notice in the total mechanical energy of the system?
- It increases
- It decreases
- It becomes zero
- It remains constant
A pendulum is oscillating on either side of its rest position. The correct statement is :
- It has only the kinetic energy at its each position.
- It has the maximum kinetic energy at its extreme position.
- It has the maximum potential energy at its mean position.
- The sum of its kinetic energy and potential energy remains constant throughout the motion.
A simple pendulum while oscillating rises to a maximum vertical height of 7 cm from its rest position where it reaches its extreme position on one side. The mass of the bob of simple pendulum is 400 g and g = 10 m/s2. The total energy of the simple pendulum at any instant while oscillating is:
- 0.28 J
- 2.8 J
- 28 J
- 28000 J