A small ball hangs on a light string of length 0.8 m. It is pulled aside until the string makes 40° with the vertical and released from rest. Ignoring air resistance, find its speed v at the lowest point.
A crate is pulled 7 m along a level floor by a rope that makes 25° with the horizontal. The tension in the rope is 90 N. Find the work W done by the rope on the crate.
A 2 kg block slides 15 m down a slope at 30° to the horizontal, with a coefficient of kinetic friction of 0.1. Find the work Wf done against friction.
A car travelling at 80 km/h on a level road brakes hard and skids to a stop with its wheels locked. The coefficient of kinetic friction between the tyres and the road is 0.5. Find the stopping distance d.
A 1 kg cart is released from rest at a height of 15 m on a smooth track that leads into a vertical circular loop of radius 5 m. Find the normal force N the track exerts on the cart at the top of the loop.
A 2 kg block is released from rest at height 1 m on a smooth ramp. At the bottom it crosses a rough horizontal strip 1 m long (μ = 0.25) and then runs onto a spring (k = 5000 N/m) on a smooth surface. Find the maximum compression x of the spring.
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