21. The potential energy of an object at height h is given by:
A) ½mv²
B) mgh
C) ma
D) mg²h
22. The law of conservation of energy states that:
A) Energy is always increasing
B) Energy is lost in motion
C) Energy can neither be created nor destroyed
D) Energy depends on speed only
23. A perfectly inelastic collision means:
A) Objects bounce off each other
B) Kinetic energy is conserved
C) Objects stick together
D) Momentum is not conserved
24. If a force of 10 N is applied to a mass of 2 kg, what is the acceleration?
A) 5 m/s²
B) 2 m/s²
C) 10 m/s²
D) 20 m/s²
25. A force is said to be balanced if the net force is:
A) Zero
B) Maximum
C) Changing
D) Infinite
26. Which force causes objects to fall to the ground?
A) Friction
B) Centripetal
C) Gravity
D) Magnetic
27. If the mass of an object is doubled while keeping the force constant, its acceleration:
A) Doubles
B) Halves
C) Stays the same
D) Becomes zero
28. The momentum of an object depends on:
A) Mass only
B) Velocity only
C) Both mass and velocity
D) Acceleration only
29. Impulse is equal to:
A) Force × Time
B) Force × Distance
C) Work × Time
D) Power × Time
30. What happens to kinetic energy when velocity is doubled?
A) Doubles
B) Triples
C) Becomes four times
D) Remains the same