6135512
Description
Flashcards by Mel Hughes, updated more than 1 year ago
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Created by Mel Hughes
over 8 years ago
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| Question | Answer |
| What is the SI unit of work done? | Joule, J |
| What is the work done on an object if a force of 300N moves it a distance of 8m? | 2400J |
| What is the increase in Ep when a mass of 40kg is lifted 8m vertically? | 320 J |
| It takes 2 seconds to lift the object in Question 1. What is the power developed? | 160 W |
| A boy of mass 40kg runs at a speed of 5m/s. What is his kinetic energy? | 500J |
| When a spring is squashed and released it warms up. Why? | Some elastic potential energy is transferred by heating |
| When do objects have momentum? | When they are moving |
| What is the momentum of a 1000 kg car travelling at 30m/s? | 30000 kg m/s |
| What is the total momentum after an explosion equal to? | The total momentum before the explosion |
| Two students on roller skates stand holding each other in the playground. They push each other away. What can you say about the momentum of each student? | It is equal and opposite |
| What is impact time? | Time taken for a collision to take place |
| Why do cars have crumple zones at both the front and the rear? | Cars may be hit from either the front or the rear, in either case the crumple zone reduces the forces on the car (or increases the impact time) |
| What happens to a passenger in a head-on collision if they are not wearing a seatbelt? | They continue to move forwards when the car stops and will hit the windscreen |
| What happens to a passenger in a head-on collision if they were wearing a very narrow seatbelt? | The narrow seatbelt would not spread the force across the passengers body and might cut them |
| When is work done by a force? | When a force moves through a distance |
| What is the relationship between work and energy? | Work done = energy transferred |
| What is the unit of power? | Watt, W |
| What is the decrease in gravitational potential energy when an object of mass 6kg is lowered through a distance of 9m? | 54 J |
| What is elastic potential energy? | The energy stored in an elastic object when it is stretched or squashed |
| What is the kinetic energy of a car of mass 1200kg travelling at 30 m/s? | 540000J |
| What is the unit of momentum? | kg m/s or Ns |
| What is the momentum of a 2500kg truck travelling at 20m/s? | 50000kg m/s |
| Why is a gymnast less likely to injure herself if she lands on a thick foam mat than if she lands on a hard floor? | The thick foam mat increases the impact time compared with the hard floor, reducing the force on the gymnast |
| An electric motor is used to raise a 0.1kg mass vertically upwards. If the mass gains 2J of gravitational potential energy, calculate the height it is raised through | 2.0m |
| A trolley of mass 0.2 kg travelling at 1.5m/s to the right collides with a stationary trolley of mass 0.3kg. After the collusion they move off together. Calculate the velocity of the trolley after the collision | 0.6m/s to the right |
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