← Back to Chapter
Browsing as Guest. Answer checking, progress and bookmarks are disabled. Log in to track your work.

Practice — Work–Energy Principle and Power • Conservation of Energy in a System with Non-Conservative Forces

Helter-skelter: length of the slide
Difficulty: ★★☆
418

A helter-skelter ride has a spiral slide. The top of the slide is \(7\text{ m}\) higher than the bottom. The average frictional resistance is \(50\text{ N}\). A boy of mass \(60\text{ kg}\) slides down, starting from rest. At the bottom he has speed \(10\text{ m s}^{-1}\).

Find the length of the slide.

Enter just the number.

Log in to check answers and record progress. You can still view solutions.
Helter-skelter: mechanical energy lost
Difficulty: ★☆☆
419

A helter-skelter ride has a vertical drop of \(7\text{ m}\). A boy of mass \(60\text{ kg}\) starts from rest and reaches the bottom with speed \(10\text{ m s}^{-1}\).

Work out the amount of mechanical energy lost.

Enter just the number in joules.

Log in to check answers and record progress. You can still view solutions.
Helter-skelter: energy change
Difficulty: ★☆☆
420

A boy slides down a helter-skelter and some mechanical energy is lost because of friction.

What form of energy has most of this lost mechanical energy been changed into?

Log in to check answers and record progress. You can still view solutions.
Box on a rough slope: coefficient of friction
Difficulty: ★★★
421

A box of mass \(10\text{ kg}\) slides \(3\text{ m}\) down a rough slope inclined at \(30^\circ\) to the horizontal. At the top of the slope its speed is \(3.25\text{ m s}^{-1}\) and at the bottom its speed is \(5\text{ m s}^{-1}\).

Find the coefficient of friction between the box and the slope.

Enter just the number.

Log in to check answers and record progress. You can still view solutions.
Sack on a ramp: energy dissipated
Difficulty: ★☆☆
422

A sack of mass \(12\text{ kg}\) slides down a ramp, starting from rest at a height of \(2\text{ m}\) above the ground. It reaches the ground with speed \(6\text{ m s}^{-1}\).

Work out the amount of mechanical energy dissipated.

Enter just the number in joules.

Log in to check answers and record progress. You can still view solutions.
Skydiver: average resistance with parachute open
Difficulty: ★★★
423

A skydiver of mass \(80\text{ kg}\) falls \(1000\text{ m}\) from rest and then opens the parachute for the remaining \(2000\text{ m}\) of the fall. Air resistance is negligible until the parachute opens. The skydiver is travelling at \(5\text{ m s}^{-1}\) just before hitting the ground.

Find the average resistance force while the parachute is open.

Enter just the number in newtons.

Log in to check answers and record progress. You can still view solutions.
Tile on a roof: frictional force
Difficulty: ★★★
424

A tile of mass \(1\text{ kg}\) slides \(3\text{ m}\) down a roof inclined at \(20^\circ\) to the horizontal. The tile then falls \(5\text{ m}\) under gravity and hits the ground with speed \(10.5\text{ m s}^{-1}\).

Find the frictional force between the tile and the roof.

Enter just the number in newtons.

Log in to check answers and record progress. You can still view solutions.
Model racing car: distance travelled
Difficulty: ★★☆
425

A model racing car of mass \(50\text{ g}\) is released from rest at the top of a downward-sloping track. The resistance to the motion of the car is \(0.05\text{ N}\). The car comes to rest on a horizontal piece of track that is \(2\text{ m}\) lower than the top of the track.

Find the distance that the car has travelled.

Enter just the number in metres.

Log in to check answers and record progress. You can still view solutions.
Diver: height at the highest point
Difficulty: ★★★
426

A diver jumps from a board \(10\text{ m}\) above a swimming pool. The diver has initial velocity \(u\text{ m s}^{-1}\) upwards. The horizontal component of motion is negligible. A constant resistance of \(0.5\text{ N kg}^{-1}\) acts on the diver.

Find an expression for the height of the diver above the pool at the highest point of the dive.

Log in to check answers and record progress. You can still view solutions.
Golf ball and pond: speed before hitting the water
Difficulty: ★★★
427

A golf ball of mass \(45.9\text{ g}\) is hit from a tee with speed \(50\text{ m s}^{-1}\). The ball lands in a pond \(5\text{ m}\) lower than the tee after travelling along a curved path of length \(160\text{ m}\). The resistance acting on the ball has magnitude \(0.3\text{ N}\).

Find the speed of the ball just before it hits the water.

Enter just the number.

Log in to check answers and record progress. You can still view solutions.
Golf ball and pond: depth of the pond
Difficulty: ★★★
428

A golf ball of mass \(45.9\text{ g}\) hits the pond with speed \(22.5\text{ m s}^{-1}\). The water immediately absorbs \(8\text{ J}\) of energy from the ball. The ball then sinks vertically and just comes to rest at the bottom. The resistance acting on the ball in the water is \(3\text{ N}\).

Find the depth of the pond.

Enter just the number in metres.

Log in to check answers and record progress. You can still view solutions.
Golf ball: average resistance force
Difficulty: ★★★
429

A golf ball of mass \(45.9\text{ g}\) is hit from a tee with speed \(180\text{ km h}^{-1}\). The ball rises to a height of \(20\text{ m}\), having travelled along a curved path of length \(61.875\text{ m}\). At the highest point of its path the ball is travelling at \(144\text{ km h}^{-1}\).

Find the magnitude of the average resistance force acting on the ball.

Enter just the number in newtons.

Log in to check answers and record progress. You can still view solutions.
Golf ball: speed before landing on the green
Difficulty: ★★★
430

A golf ball of mass \(45.9\text{ g}\) is hit from a tee with speed \(50\text{ m s}^{-1}\). The average resistance force is \(0.185\text{ N}\). The ball travels a total curved path length of \(61.875+105.8\text{ m}\) and lands on the green, which is \(4\text{ m}\) lower than the tee.

Find the speed of the ball just before it lands on the green.

Enter just the number.

Log in to check answers and record progress. You can still view solutions.
Golf ball: energy absorbed by the green
Difficulty: ★★☆
431

A golf ball of mass \(45.9\text{ g}\) lands on the green with speed \(35\text{ m s}^{-1}\) and is immediately brought to rest.

Find the energy absorbed by the green.

Enter just the number in joules.

Log in to check answers and record progress. You can still view solutions.
No questions left in this filter.