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Topics in NEET Physics
Which statement best describes Newton's third law of motion?
Correct Answer:
B. Action and reaction forces are equal in magnitude and opposite in direction
EXPLANATION
Newton's third law states that for every action, there is an equal and opposite reaction force.
An object of mass 8 kg is on a horizontal surface with coefficient of kinetic friction 0.25. What is the friction force when the object is moving? (g = 10 m/s²)
Correct Answer:
B. 20 N
EXPLANATION
f = μN = μmg = 0.25 × 8 × 10 = 20 N
A ball is thrown vertically upward with an initial velocity of 20 m/s. How long does it take to reach maximum height? (g = 10 m/s²)
Correct Answer:
B. 2 s
EXPLANATION
At maximum height, v = 0. Using v = u - gt: 0 = 20 - 10t, so t = 2 s
A car accelerates uniformly from rest and covers 100 m in 5 seconds. What is its acceleration?
Correct Answer:
A. 8 m/s²
EXPLANATION
Using s = ut + ½at², where u = 0, s = 100 m, t = 5 s: 100 = 0 + ½a(25), a = 8 m/s²
Two forces of 12 N and 5 N act on a body. The maximum resultant force possible is:
Correct Answer:
B. 17 N
EXPLANATION
Maximum resultant occurs when forces act in the same direction: R = 12 + 5 = 17 N
A body of mass 5 kg is moving with a velocity of 10 m/s. What force is required to stop it in 2 seconds?
Correct Answer:
A. 25 N
EXPLANATION
Using F = ma, where a = (v-u)/t = (0-10)/2 = -5 m/s². Therefore F = 5 × 5 = 25 N
An object is thrown vertically upward with initial velocity 20 m/s. At what time does it reach maximum height? (g = 10 m/s²)
Correct Answer:
B. 2 s
EXPLANATION
At maximum height, v = 0. Using v = u - gt, 0 = 20 - 10t, therefore t = 2 s
A car of mass 1000 kg experiences friction of 2000 N while moving. If the engine provides 5000 N of force, what is the net acceleration?
Correct Answer:
B. 3 m/s²
EXPLANATION
Net force = 5000 - 2000 = 3000 N. Using F = ma, a = 3000/1000 = 3 m/s²
A book rests on a table. The normal force on the book is 10 N. What is the weight of the book? (g = 10 m/s²)
Correct Answer:
B. 1 kg
EXPLANATION
At rest, normal force equals weight. N = mg, 10 = m × 10, therefore m = 1 kg
A 2 kg mass is subjected to forces of 3 N (east) and 4 N (north). What is the magnitude of acceleration?
Correct Answer:
C. 2.5 m/s²
EXPLANATION
Net force = √(3² + 4²) = 5 N. Using F = ma, a = 5/2 = 2.5 m/s²
