P3.2

Question 1

Why are liquids used in hydraulics?

Answer 1

~ They’re virtually incompressible (pressure is the same throughout)
~ They flow

Question 2

What does the process of using hydraulics involve?

Answer 2

Moving things using liquids to transfer forces

Question 3

What is pressure measured in?

Answer 3

Pascals (Pa)

1Pa = 1N per m2

Question 4

What is the centripetal force due to?

Answer 4

~ Gravity
~ Friction
~ Tension

Question 5

What would happen if there was no centripetal force on a roundabout?

Answer 5

The person would fly off in a straight line

Question 6

Where does the centripetal force act?

Answer 6

Towards the centre

Question 7

Where is the centre of mass?

Answer 7

The point that the mass appears to act from

Question 8

What are 2 ways to keep something more balanced?

Answer 8

~ Wider base

~ Lower centre of mass

Question 9

When is something unbalanced?

Answer 9

When the line of action of weight is outside of the base

Question 10

What causes the centripetal force needed to make an object move in a circle increase?

Answer 10

~ An increase in mass
~ An increase in speed
~ A decrease in size of circle

Question 11

How does increasing the length of the pendulum affect the period?

Answer 11

The longer the pendulum, the larger the period

Question 12

What is the resultant force on an object moving in a circle?

Answer 12

The centripetal force, which causes the acceleration

Question 13

What is a plumb line?

Answer 13

A piece of string with a weight attached

Question 14

What is the method for finding the centre of mass of an irregular object?

Answer 14

~ Use a drawing pin to hold plumb line freely over object
~ Pencil line is drawn where the string falls
~ These 2 steps are repeated for another 2 positions on the object
~ The C.o.M is where the 3 pencil markings cross

Question 15

What is the period of a pendulum?

Answer 15

The time taken for the pendulum to swing to the other side and back again

Question 16

How can you increase the moment or turning force?

Answer 16

~ Increase the force applied

~ Increase the perpendicular distance between the line of action of the force and the pivot

Question 17

What force causes earth to orbit in a circle?

Answer 17

The gravitational force acting on the earth

Question 18

What force causes a car to turn in a circle?

Answer 18

The frictional force acting on the wheels

Question 19

What force causes a whirling ball on string to spin in a circle?

Answer 19

The tension force in the string