Physics Triple - 3

Question 1

How do you increase the turning effect?

Answer 1

• increase the size of the force

- using something thats greater from the pivot

Question 2

How does the spanner work?

Answer 2

• Force on a spanner causes a turning effect on the moment on the nut ( nut is a pivot)
• using a longer spanner, the same force can exert a larger moment because the distance from the pivot is greater
• to get maximum moment you need to push at right angles to the spanner.
  Pushing at a smaller angle means a smaller moment as the perpendicular distance between the line of action and the pivot is smaller

Question 3

What is the centre of mass?

Answer 3

The centre of an object is the point at which an object mass maybe thought to be concentrated at

Question 4

How do you work out the centre of mass?

Answer 4

• a freely suspended object will swing until its centre of mass is vertically below the point of suspension, it rests in this position as there is no moment this is because the pivot is in the line with the line of action of the force
• the object weight acts at a distance from the pivot which creates a moment about the pivot this makes it swing until the centre of mass is at its lowest which it directly below the pivot

Question 5

How do you find the centre of mass?

Answer 5

1. Suspend shape and a plumb line from the same point
2. Wait until they stop moving
3. Draw a line along plumb line
4. Do same thing but from a different pivot point
5. Centre of mass is where the two lines cross
   Or in a symmetrical shape look for the lines of symmetry

Question 6

What is the principle of moments?

Answer 6

Total anti-clockwise moments= total clockwise moments

Question 7

What do levers do?

Answer 7

Levers increase the distance from the pivot at which the force is applied this means less force is needed to get the same moment

Question 8

What happens if the moments are not equal?

Answer 8

If the total clockwise moment does not equal the total anti-clockwise moment than there will be a resulting moment

Question 9

What do the most stable objects have?

Answer 9

Wide base

Or clamped base down

Question 10

What happens if the centre of mass moves over its base?

Answer 10

It will begin to tip over snd move beyond the edge of its base
If the line of action of the weight of the object lies outside the base of the object it will cause a resultant moment and the object will tip over

Question 11

What is the time period of a pendulum?

Answer 11

Its the time period for pendulum to swing from one side to the other and back again
- the time period is always the same

Question 12

What does the time period depend on?

Answer 12

The time for one pendulum depends on its length

- the longer the pendulum the greater the time period

Question 13

What is a hydraulic?

Answer 13

When the pressure in a liquid is transmitted equally in all directions

Question 14

What is a moment?

Answer 14

A moment is the turning effect of a force

Question 15

Why is the pressure in a liquid transmitted equally in all directions?

Answer 15

• virtually compressible so you cannot squash them as there volume and density remains the same
• because they are incompressible when a force is applied to a single point it will be transmitted to other parts of the liquid thus the pressure is transmitted throughout the whole liquid

Question 16

Whats a good thing about a hydraulic machine?

Answer 16

The force of a hydraulic machine is greater than the force applied to it

Question 17

How does a hydraulic car machine work?

Answer 17

The handle is pressed and the oil is forced out of a narrow cylinder into a wider cylinder. The pressure of the oil forces the wider cylinder outwards and the piston forces pivot leaver to raise the car

Question 18

What is velocity when travelling in a circle?

Answer 18

Velocity is constantly changing because velocity is speed in a constant direction and when a object is travelling in a circle its constantly changing direction therefore the object accelerating

Question 19

What is acceleration?

Answer 19

How quickly velocity is changing

Question 20

When an object is travelling in a circle which way is accelerating going?

Answer 20

Towards the centre of the circle, this is because there must be a resultant force acting on the object this force acts towards the centre of the circle

Question 21

What is a centripetal force?

Answer 21

The force that keeps something in a circle moving around

- acts towards the centre of the circle

Question 22

What does the centripetal force depend on?

Answer 22

• Mass
  The larger the mass of an object the bigger the centripetal force has to be to keep it moving in a circle
• speed
  The faster an object the bigger the centripetal force has to be go keep it moving in a circle
• radius
  A larger force is required to keep something in a smaller circle as there is more turning to do