Laws of Motion

A force of 15 N acts on a body of mass 3 kg, initially at rest. What is its acceleration?

A 0.5 kg ball moving at 10 m/s is brought to rest in 0.2 s by a goalkeeper. Find the average force applied.

A bat strikes a 0.2 kg ball, reversing its velocity from 20 m/s to 15 m/s in the opposite direction. Find the magnitude of the impulse delivered.

A horizontal force of 20 N is applied to a 3 kg block, which is connected by a string to a 2 kg block placed behind it (the string pulls the 2 kg block along). Find the tension in the string. Surface is frictionless.

Masses of 5 kg and 3 kg hang on either side of a frictionless, massless pulley (Atwood machine). Find the acceleration of the system. (g = 10 m/s²)

A 60 kg man stands on a weighing scale inside a lift accelerating upward at 2 m/s². What does the scale read? (g = 10 m/s²)

The cable of the lift in the previous question suddenly snaps, and the lift falls freely. What does the scale now read?

A 4 kg block rests on a horizontal surface with μₛ = 0.3. A horizontal force of 10 N is applied to it. What is the force of friction acting on the block? (g = 10 m/s²)

A 2 kg block slides on a horizontal surface with μ_k = 0.25. Find its deceleration due to friction. (g = 10 m/s²)

The coefficient of static friction between a body and an inclined surface is 0.5. Find the angle of repose.

A 5 kg block slides down a 30° rough incline with μ_k = 0.2. Find its acceleration down the slope. (g = 10 m/s²)

A spring with force constant k = 200 N/m is stretched by a force of 50 N. Find the extension produced.

A pendulum hangs from the ceiling of a train accelerating at 5 m/s². Find the angle the string makes with the vertical, as seen by a passenger inside the train. (g = 10 m/s²)

A gun recoils backward when a bullet is fired forward from it. This is best explained by:

A 5 kg block rests on a 10 kg block, which lies on a frictionless floor. The coefficient of friction between the two blocks is 0.3. A horizontal force F is applied to the bottom (10 kg) block. Find the maximum value of F for which both blocks move together. (g = 10 m/s²)

A 4 kg block hangs from a string passing over a frictionless pulley and is connected to a 6 kg block resting on a rough horizontal surface (μ = 0.25). Find the acceleration of the system. (g = 10 m/s²)

A 2 kg block on a horizontal surface is pulled by a force of 10 N directed at 30° above the horizontal. Find the normal reaction on the block. (g = 10 m/s²)

A bomb of mass 10 kg at rest explodes into two fragments of mass 4 kg and 6 kg. The 4 kg fragment moves off at 6 m/s. Find the speed of the 6 kg fragment.