Solved Problems on Laws of Motion - Science
SOLVED PROBLEMS
Problem-1
Calculate the velocity of a moving body of mass 5 kg whose linear momentum is 2.5 kg m s–1.
Solution:
Linear momentum = mass × velocity
Velocity = linear momentum / mass. V = 2.5 / 5 = 0.5 m s–1
Problem 2
A door is pushed, at a point whose distance from the hinges is 90 cm, with a force of 40 N. Calculate the moment of the force about the hinges.
Solution:
Formula: The moment of a force M = F × d
Given: F = 40 N and d = 90 cm = 0.9 m.
Hence, moment of the force = 40 × 0.9 = 36 N m.
Problem 3
At what height from the centre of the Earth the acceleration due to gravity will be 1/4th of its value as at the Earth.
Solution:
Data: Height from the centre of the Earth, Rʹ = R + h
The acceleration due to gravity at that height, gʹ = g/4
From the centre of the Earth, the object is placed at twice the radius of the earth.