Work Energy and Power Test

Result

Work Energy and Power Test - 6

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Weekly Quiz Competition

Question 1
1 / -0

in an elastic collision

A
the total kinetic energy of the system is less than the total kinetic energy before

B
the total kinetic energy of the system is greater than the total kinetic energy before

C
the total kinetic energy of the system is the zero after the collision.

D
the total kinetic energy of the system is the same after the collision as before.

Solution

kinetic energy is transferred to other forms of energy—such as thermal energy, potential energy, and sound—during the collision process. After collision if recovery of kinetic energy is 100% then it is called elastic collision.So that in an elastic collision the total kinetic energy of the system is the same after the collision as before.
Question 2
1 / -0

in an inelastic collision

A
the total kinetic energy of the system is the zero after the collision.

B
the total kinetic energy of the system is the same after the collision as before

C
the total kinetic energy of the system is greater than the total kinetic energy before

D
the total kinetic energy after the collision is less than before the collision

Solution

kinetic energy is transferred to other forms of energy—such as thermal energy, potential energy, and sound—during the collision process. After collision if recovery of kinetic energy is less than % then it is called inelastic collision i.e.. some part of kinetic energy is not recover. So that in an inelastic collision the total kinetic energy after the collision is less than before the collision
Question 3
1 / -0

In a completely inelastic collision

A
the colliding bodies move in same direction after the collision

B
the colliding bodies move at an angle after the collision

C
the colliding bodies move in opposite directions after the collision

D
the colliding bodies stick together and move as one body after the collision

Solution

For perfectly Inelastic collision coefficient of restitution is zero.

coefficient of restitution e= relative velocity of separation / relative velocity of approach

e = 0

so that relative velocity of separation will be zero means the colliding bodies stick together and move as one body after the collision
Question 4
1 / -0

A dog weighing 25 kg, while chasing a cat, jumps over a fence of height 1.6 m. What is the potential energy of dog at the top of fence?
(Take gravity due to earth 'g'=10 m s^-2)

A
160 Joules

B
380 Joules

C
480 Joules

D
320 Joules

Solution

380 Joules
Question 5
1 / -0

The casing of a rocket in flight burns up due to friction. At whose expense is the heat energy required for burning obtained?

A
atmosphere

B
earth’s gravitational energy

C
reaction force energy

D
Rocket

Solution

Heat energy required for burning of casing of rocket comes from the rocket itself. As a result of work done against friction the kinetic energy of rocket continuously deceases and this work against friction reappears as heat energy. This results in reduction of the mass of the rocket.