Using Physics to Make Things Work

Question 0

Give an example of a moment

Answer 0

A spanner used to unscrew a wheel nut. The moment would be on the nut

Question 1

What is a moment?

Answer 1

A turning force

Question 2

How do you increase the moment?

Answer 2

Increase the force applied

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

Question 3

Distance between line of action and pivot must be…

Answer 3

Perpendicular

Question 4

If a pivot is close to the load, the load is easier/harder to pick up

Answer 4

Harder?

Question 5

A force is exerted quite far away from the pivot. Does this make it easier or harder to pick up? Why?

Answer 5

Easier because is magnifies the effective force

Question 6

What is centre of mass?

Answer 6

The point where there is an equal amount of mass in all directions

Question 7

How can you find the centre of mass of a symmetrical object?

Answer 7

Where the lines of symmetry cross

Question 8

How do you find the centre of mass of an unusual shape?

Answer 8

1. Hang the shape and a plumb line from a pout so both are free to rotate
2. Mark position of plumb line
3. Hang shape from different point and mark plumb line
4. Centre of mass is where they cross which can be checked by balancing it on you finger

Question 9

How is the length of a pendulum measured?

Answer 9

From the point of pivot to the centre of mass

Question 10

What affects the time period of a pendulum?

Answer 10

Length- longer pendulum will have longer time period

Question 11

What are the moments doing when an object is not turning or balanced?

Answer 11

Total clockwise moment is equal to total anticlockwise moment

Question 12

What will make an object topple over?

Answer 12

If the line of action of its weight lies outside its base

The weight causes a turning effect so the object falls over

Question 13

What increases stability in cars?

Answer 13

Low centre of mass

Wide wheel base

Question 14

Why are liquids used in hydraulics?

Answer 14

Because they are virtually incompressible

Question 15

If a force is applied to a small area it…

Answer 15

Produces a bigger pressure than on a bigger area

Question 16

If the pressure acts on a bigger area…

Answer 16

It will exert a bigger force than on a smaller area

Question 17

Where are hydraulics often used?

Answer 17

Car breaks

Question 18

If pressure is put on the small piston of a hydraulic, more/less pressure is produced on the big piston

Answer 18

More

Question 19

If pressure is put on the big piston of a hydraulic, more/less pressure is produced on the small piston

Answer 19

Less

Question 20

When an object moves continuously in a circle…

Answer 20

It continually accelerates towards the centre of the circle

Question 21

What changes when an object accelerates towards the centre of a cirlce?

Answer 21

Velocity

NOT speed

Question 22

What is centripetal force?

Answer 22

The inward force on an object causing it to move in a circular path

Question 23

How do centripetal forces act on a car as it turns corners?

Answer 23

Frictional forces on the turned wheels allow the car to turn

Question 24

How do centripetal forces act on the earth as it orbits the sun?

Answer 24

Gravitational force acting on the earth

Question 25

How do centripetal forces act in a ball whirling around on string?

Answer 25

Tension in the string

Question 26

How can centripetal force be increased?

Answer 26

Increasing mass of object
Increasing speed of object
Decreasing radius