OCR AS Physics revision thread.

Here are some revision questions.

Forces and motion
What is the difference between a scalar and a vector?
Describe the independent nature of perpendicular components of a vector.
Define displacement, speed, velocity and acceleration.
What does the slope of a displacement-time graph give?
What does the slope of a distance-time graph give?
What does the slope of a velocity-time graph give?
Derive the suvat equation; s = ½(u+v)t
Define mass.
What is the S.I unit of density and pressure?
Define the newton.
Define weight.
Define tensile and compressive force.
Define the terms; Young modulus, elastic limit, stress and strain.
Distinguish between elastic and plastic deformation of a material.
Define motive force and braking force.
Describe how driving wheels can generate a motive force.

Reply 1

Invincible

Widowmaker

Here are some revision questions.

Forces and motion

Define the newton.
Define weight.
Define tensile and compressive force.
Define the terms; Young modulus, elastic limit, stress and strain.
Distinguish between elastic and plastic deformation of a material.
Define motive force and braking force.
Describe how driving wheels can generate a motive force.

what are the answers to these questions pls?

Reply 2

Christophicus

OP

18

Define the newton.
The force that accelerates a mass of 1kg by 1ms^-2.

Define weight.
The force caused by a gravitational field acting on an object's mass.

Define tensile and compressive force.
A tensile force is a force that stretches an object.
A compressive force is a force that squashes an object.

Define the terms;
Young modulus - the ratio of stress to strain of a material = stress/strain
elastic limit - The point beyond which an object will not return to its original length.
stress - the ratio of extension to the natural length of a material = extension/original length
strain - the ratio of the load to the area of the object where the force is applied = force/area

Distinguish between elastic and plastic deformation of a material.
elastic deformation occurs when the stress is below the elastic limit. The material will return to its original length. It is temporarily deformed.
plastic deformation occurs when the stress is above the elastic limit. The material will not return to its original length. It is permanently deformed.

Define motive force and braking force.
motive force - the force produced by a motor vehicle's engine which causes it to accelerate.
braking force - the force produced by the brakes which causes the vehicle to slow down.

Describe how driving wheels can generate a motive force.
The engine drives the wheel round. The bottom of the tyre (where it is in contact with the road surface) is trying to move backwards. It pushes backwards on the road; provided the road is not slipperly, there is a frictional force forwards, exerted by the road on the tyre. This force propels the car forwards.

Reply 3

marthafocker

In wave properties what is the fundamental when talking about waves

Reply 4

Christophicus

OP

18

marthafocker

In wave properties what is the fundamental when talking about waves

fundamental frequency => 1 node, 1 antinode.

Reply 5

marthafocker

that would mean fundamental frequency wave is λ/2

however in the may 2002 paper question 5)b) the fundamental is λ/4 (one node, one antinode) why is this?

Reply 6

OldakQuill

4

Widowmaker

Here are some revision questions.

Forces and motion
What is the difference between a scalar and a vector?
Describe the independent nature of perpendicular components of a vector.
Define displacement, speed, velocity and acceleration.
What does the slope of a displacement-time graph give?
What does the slope of a distance-time graph give?
What does the slope of a velocity-time graph give?
Derive the suvat equation; s = ½(u+v)t
Define mass.
What is the S.I unit of density and pressure?
Define the newton.
Define weight.
Define tensile and compressive force.
Define the terms; Young modulus, elastic limit, stress and strain.
Distinguish between elastic and plastic deformation of a material.
Define motive force and braking force.
Describe how driving wheels can generate a motive force.

1. A vector has magnitude AND direction, a scalar has only magnitude.
2. The veritcle and horizontal elements of a vector are independent eg. the horizontal and verticle velocity of a bullet are independent. A bullet with 100 m/s horizontal velocity will hit the ground when shot from 1 metre as the same bullet with 0 m/s horizontal velocity.
3. Displacement is the distance moved from a point in a straight line and in one direct. Speed is the change in distance per unit time. Velocity is the change in displacement per unit time. Acceleration is the change in velocity per unit time.
4. Velocity
5. Speed
6. Acceleration
7. ave. vel. = s/t = ½(u+v) Therefore s = ½(u+v)t
8. Mass is a measure of amount of matter
9. Kilogram per cubic meter [no actual SI unit] & pascal
10. A newton is the force required to accelerate a mass of 1 kg 1 m s^-2
11. Weight is mass subject to gravity (mg)
12. Tensile - pulling apart; compressive - pushing together
13. Young's modulus = stress/strain (Fl/eA); elastic limit is the point of stretching beyond which a substance will no longer return to its original shape; stress = F/A; strain = e/l
14. Elastic deformation - material returns to original shape; plastic - doesn't
15. Motive force is the driving force provided by the engine; braking force is the force exerted by the wheels on the road when stopping?
16. Friction :wink: