3.1: A force of 20 N moves a body with an acceleration of 2 ms⁻². What is its mass? Ans. (10 kg)


3.2: The weight of a body is 147 N. What is its mass? (Take the value of g as 10 ms⁻² ) Ans. (14.7 kg)

3.3: How much force is needed to prevent a body of mass 10kg from falling? Ans. (100 N)


3.4: Find the acceleration produced by a force of 100 N in a mass of 50 kg. Ans. (2 ms⁻² )


3.5: A body has weight 20 N. How much force is required to move it vertically upward with an acceleration of 2 ms⁻² ? Ans. (24 N)


3.6: Two masses 52 kg and 48 kg are attached to the ends of a string that passes over a frictionless pulley. Find the tension in the string and acceleration in the bodies when both the masses are moving vertically. Ans. (500 N,0.4 ms⁻²)


3.7: Two masses 26 kg and 24 kg are attached to the ends of a string which passes over a frictionless pulley. 26 kg mass is lying over a smooth horizontal table. 24 N mass is moving vertically downward. Find the tension in the string and the acceleration in the bodies. Ans. 125 N, 4.8 ms⁻²)


3.8: How much time is required to change 22 Ns momentum by a force of 20 N ? Ans. (1.1s)

3.9: How much is the force of friction between a wooden block of mass 5 kg and the horizontal marble floor? The coefficient of friction between wood and the marble is 0.6. Ans. (30 N)


3.10: How much centripetal force is needed to make a body of mass 0.5 kg to move in a circle of radius 50cm with a speed 3 ms⁻¹ ? Ans. (9 N)