Using Physics To Make Things Work

Question 1

How do you increase the moment

Answer 1

Either the force must increase

Or the distance to the pivot must increase

Question 2

Why is it easier to undo a wheel nut with a long spanner than a short one

Answer 2

The longer spanner increases the distance between the line of action of the force and the pivot

Question 3

What is used to make a Job easier

Answer 3

A lever

Question 4

What is the load

Answer 4

The weight of an object raised by a device used to lift the object or the force applied by a device when it is used to to shift an object

Question 5

What is the effort

Answer 5

The force applied to a device used to raise a weight or shift an object

Question 6

What does a lever act as

Answer 6

A force multiplier, so the effort we apply can be much less than the load

Question 7

What’s a moment

Answer 7

The turning effect of a force

Question 8

What are moments measured in

Answer 8

Newton metres

Question 9

What is the line of action p

Answer 9

The line along which a force acts

Question 10

What is a pivot

Answer 10

The point about which an object turns when acted on by a force that makes it turn

Question 11

What is the centre of mass

Answer 11

The point where an objects mass may be thought to be concentrated

Question 12

What is equilibrium

Answer 12

The state at which an object is as rest

Question 13

How can you find the centre of mass of a thin irregular sheet of a material

Answer 13

Suspend the thin sheet from a pin held in a clamp stand. Because it is freely suspended, it is able to turn
When it comes to rest, hang a plumbline from the same pin
Mark the position of the plumbline against the sheet
Hang the sheet with the pin at another point and repeat the procedure
The centre of mass is where the lines that marked the position of the plumbline cross

Question 14

What does the position of the centre of mass depend on

Answer 14

The shape of the object and it sometimes lies on the outside of the object

Question 15

Where is the centre of mass for a symmetrical object

Answer 15

Along the axis of symmetry, if the object has many symmetry lines the centre of mass is where the lines of symmetry meet

Question 16

If an object is in equilibrium it is …..

Answer 16

Balanced

Question 17

If you take the moments at any point what will you find

Answer 17

The total clockwise moment and the total anti-clockwise moments are equal

Question 18

What is the principle of moment

Answer 18

For an object in equilibrium, the sum of all the clockwise moments about any point = the sum of all the anti-clockwise moments about that point

Question 19

What does the line of action of the weight of an object act through

Answer 19

The centre of mass

Question 20

What is a resultant moment

Answer 20

The difference between the sum of the clockwise moments and the anti-clockwise moments about the same point if they are not equal

Question 21

If the line of action of the weight lies outside the base of an object what happens

Answer 21

There will be a resultant moment and the object will topple over

Question 22

The wider the base of an object and the lower its centre of mass……..

Answer 22

Further it has to tilt before the line of action of the weight moves outside the base

Question 23

How is the stability of an object increased

Answer 23

Making its base widget and its centre of mass lower

Question 24

What is pressure measured in

Answer 24

Pascals, Pa or N/m2

Question 25

Liquids are ….

Answer 25

Virtually incompressible and the pressure in a liquid is transmitted equally in all directions

Question 26

A force exerted on a liquid …..

Answer 26

Will be transmitted to other points in the liquid

Question 27

What are some examples of principle of moments

Answer 27

Seesaw a and balance scales

Question 28

What does the force exerted by a hydraulic pressure system depend on

Answer 28

The force exerted on the system
The area of the cylinder on which this force acts
The area of the cylinder that exerts the force

Question 29

Why can hydraulic systems be used as a force multiplier

Answer 29

The use of different cross sectional areas on the effort and load sides of the system mean it can be used as a force multiplier

Question 30

When an object moves in a circle it is constantly moving in a different direction…….

Answer 30

So it is continuously changing velocity

Question 31

What is centripetal acceleration

Answer 31

The acceleration of an object moving in a circle acting on a object moving in a circular path which always acts towards the centre of the circle

Question 32

If the centripetal force stops acting …….

Answer 32

The object will continue to move in a straight line at a tangent to the circle

Question 33

the centripetal force needed to make an object perform circular motion increases as …..

Answer 33

The mass of the object increases
The speed of the object increases
The radius of the circle decreases

Question 34

What is oscillating motion

Answer 34

Moving to and fro along the same line

Question 35

What does a simple pendulum consist of

Answer 35

A mass, called a bob suspended on the end of a string

Question 36

What happens when the Bob is displaced to one side and let go

Answer 36

The pendulum oscillates back and forth through the equilibrium position

Question 37

What is The amplitude of the oscillation

Answer 37

The distance from the equilibrium position to the highest position on either side

Question 38

What is the time period of the oscillation

Answer 38

The time taken for one complete cycle which is
The time taken from the highest position on one side to the highest position on the other side and back to the start position
The time taken between successive passes in the same direction through the equilibrium position.

Question 39

How do you calculate the time period

Answer 39

To measure the time period of a pendulum we can measure the average time for 20 oscillations and divide the timing by 20

Question 40

What does the time period depend on

Answer 40

The length of the pendulum and increase as its length increases

Question 41

What is the frequency of the oscillations

Answer 41

The number of complete cycles of oscillation per second

Question 42

Why will a swing come to rest if not pushed

Answer 42

Energy is transferred due to friction at the top of the swing and due to air resistance