Work and Energy

Question 1

Work done (J)
Energy transferred

Answer 1

Force(N) X Distance (M)

Question 2

Kinetic Energy

Answer 2

Energy of a moving object

Question 3

(Gravitional) Potential Energy

Answer 3

Energy an object has because of its position
GPE(J) = Mass (Kg) X Acceleration of free fall (m/s)2 X Change in height (m)

Question 4

Law of conversation of energy

Answer 4

Energy cant be created or destroyed only transferred from one form to another

Question 5

Objects falling downwards

Answer 5

PEloss = Ke gain + work done by air resistance and/or friction

Question 6

Objects thrown upwards

Answer 6

KE loss = PEgain + work done by air resistance and/or friction

Question 7

Seat belts

Answer 7

Keeps you in your seat during a crash. It does not hold you rigidly in position. The end of the belt is wound over an inertia real which clamps the belt firmly whenever there is sudden force on it but allows it to be pulled out slowly when it is being fastened. Belt is designed to strech by about 0.25m in a crash and allows the force holding you in place to act over a longer time. A longer time means a smaller force.

Question 8

Crumple zones

Answer 8

Parts of the car at the front and rear. Designed to squash or crumple easily in the event of a crash. Kinetic Energy of a moving car is absorbed by the crumpling because work is done in causing the metal to deform. Crumpling also lengthens the impact time and reduces the force which is transmitted to the passengers. The area where the passengers are housed is made of much thicker gauge metal which forms a rigid protective cage around the passengers.

Question 9

Air Bags

Answer 9

Provide a soft yielding cushions between the persons upper body and the steering wheel or dashboard. Injuries which could result in the event of a crash are virtually eleminated by the deployment of the bag because;
Moving persons kinetic energy is absorbed as a result of the work done in deformation of the bag
Impact time is increased to give a decrease in the size of the impact force

Question 10

Side Impact Bars

Answer 10

Lessen the amount of bodywork distortion produced inside the passenger compartment during a crash. Side Impact Bars cause the energy created during a collision to be directed to the floor or roof etc. These structures absorb the enery and so reduce damage and intrusion to the passenger department and so protect the passengers from severe injuries

Question 11

Hooke’s Law

Answer 11

An elastic object is stretched the increased lenght is called the extension
Force (N) = Spring constant (N/M) X Extension (m)

Question 12

Spring Constant

Answer 12

Found by carrying out an experiment.

Question 13

Work done in stretching

Answer 13

= Area under force extension F-X graph
W= 1/2 FX for a linear relationship