If the body of mass 2 kg dropped from the height of 5 m find its momentum (g =10ms-2):
Correct answer: B. 20 N s
- A. 15 N s
- B. 20 N s
- C. 30 N s
- D. 40 N s
Explanation
To solve this problem, we first calculate the final velocity of the body using the principle of conservation of energy. The gravitational potential energy at the height of 5 m is converted into kinetic energy as the body falls.The potential energy (PE) at the height can be given as PE = mgh = 2 kg * 10 m/s2 * 5 m = 100 J.This energy is converted into kinetic energy (KE), which is KE = 0.5 * m * v2. Equating the two gives: 100 = 0.5 * 2 * v2. Solving for v gives v = √(2 * 10 * 5) = √100 = 10 m/s.The momentum (P) is calculated using the formula P = mv = 2 kg * 10 m/s = 20 N s.Option A (15 N s) and Option C (30 N s) do not match the calculated momentum. Option D (40 N s) is a significant overestimate, possibly from a miscalculation. Therefore, Option B is the correct choice.
Last updated
About Force and Motion
Displacement, velocity and acceleration describe motion, including the horizontal and vertical components of projectile motion. The chapter connects these quantities with Newton's laws, momentum and impulse, then applies conservation of momentum to collisions, distinguishing elastic collisions from inelastic ones.
Practise Force and Motion
1,416 free Force and Motion MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Physics questions like this
Physics is on 13 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
(1, 1, 1) . (2, 2, 2)
1st law of motion gives the definition of:
2nd law of motion measures which quantity?
7.0 kg bowling ball experience a net force of 5.0N. What will be its acceleration?
A 0.2 kg rubber ball is dropped from the window of a building. It strikes the sidewalk below at 30m/s and rebounds up at 20m/s. The impulse on the ball during the collision is: