# Physics Unit 3

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• Created by: camKD
• Created on: 06-04-14 12:01
Give two similarities between an eye and a camera.
Any two from: -both use a covering lens -image formed is real -image is inverted -image in eye formed on retina, image in camera formed on film/CCDs -amount of light entering eye and camera can be controlled
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Why must a radiographer go behind a screen before switching on the X-ray machine?
-X-rays are ionising so they can damage cells -any stray X-rays are absorbed my the screen -which reduces the radiation dose to the radiographer
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Give the advantage of a CT scan over an X-ray
-a CT scan gives a 3D image -therefore the image can be observed from different directions
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Riders at a fairground ride spin in a rotating cylinder as the floor is dropped. How is it that the cylinder is rotating at a constant speed but at the same time the riders inside the cylinder are accelerating?
The direction of the riders is constantly changing, therefore the velocity of the riders is changing, and because acceleration is the rate of change of velocity the acceleration is changing
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... In which direction do the riders accelerate? What is the name given to the force that causes the riders to accelerate?
Towards the centre. Centripetal.
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How can you change the design of a vehicle to make it more stable?
Lower the centre of mass and make the wheelbase wider.
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Refer to diagram: why does the tractor not topple over?
-the line of action of its weight -falls inside its wheel base -therefore there is no resultant/clockwise moment
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## Other cards in this set

### Card 2

#### Front

Why must a radiographer go behind a screen before switching on the X-ray machine?

#### Back

-X-rays are ionising so they can damage cells -any stray X-rays are absorbed my the screen -which reduces the radiation dose to the radiographer

### Card 3

#### Front

Give the advantage of a CT scan over an X-ray

### Card 4

#### Front

Riders at a fairground ride spin in a rotating cylinder as the floor is dropped. How is it that the cylinder is rotating at a constant speed but at the same time the riders inside the cylinder are accelerating?

### Card 5

#### Front

... In which direction do the riders accelerate? What is the name given to the force that causes the riders to accelerate?