Work, energy and simple machines A2 20-31

Question 1

What are contact forces?

Answer 1

They act when surfaces are in contact.

Question 2

Name some examples of contact forces

Answer 2

• Air resistance
• Friction

Question 3

What are drag forces?

Answer 3

The force that slows down an object moving in a fluid, as it has to push the fluid to move.

Question 4

Name some examples of drag forces.

Answer 4

• Water resistance
• Air resistance

Question 5

Name 2 things that an object does when the resultant force is zero.

Answer 5

• It stops moving
• It moves in the same direction in a constant speed.

Question 6

What is deformation

Answer 6

Forces changing the shape of an object.

Question 7

What is caused by forces streching an object?

Answer 7

Tension

Question 8

What is caused by forces squashing an object?

Answer 8

Compression

Question 9

how would reaction force work?

Answer 9

When you apply force on something, your weight pushes particles together, cuasing the bonds to get compressed, then they push back and support you. That support created is called the Reaction Force

Question 10

What is meant by an extension in stretching.

Answer 10

The amount a material stretchs from its original position.

Question 11

What is an Elastic limit

Answer 11

The limit of how much an elastic object can stretch until it physically cannot return back to its original state.

Question 12

How does Hookes Law work

Answer 12

When the object’s extension doubles when you double the force it obeys Hooke’s Law.

Question 13

What is Moment?

Answer 13

The turning force on a object.

Question 14

What is the formula to calculate moment?

Answer 14

Force (N) x Distance from the pivot (m) = Moment (Nm)

Question 15

What do you mean when an object is in equilibrium.

Answer 15

The sum of clockwise moment is equal to the sum of the anticolockwise moments.

Question 16

How is fluid pressure produced?

Answer 16

Gases and Liquids (fluids) have atoms and molecuels that collide against surfaces to produce fluid pressure.

Question 17

What is the equation for calculating fluid pressure

Answer 17

Force (N) / Area (m2) = Fluid Pressure (N/m2)

Question 18

How can you increase gas pressure?

Answer 18

• Heat the gas
• Squash the gas

Question 19

Define atmospheric pressure.

Answer 19

Pressure exerted by the weight of the air around you.

Question 20

Why does atmospheric pressure decrease as altitude increases?

Answer 20

There are less air molecules, as they get pulled lower towards earth’s gravity.

Question 21

Define liquid pressure

Answer 21

Pressure exerted by aliquid on a specific area.

Question 22

Why are liquids incompressible?

Answer 22

There a very little gaps between liquid particles unlike gas particles.

Question 23

Why is the wall of a dam not straight?

Answer 23

Because the liquid pressure is greater at the bottom, so the wall curves outwards.

Question 24

How does upthrust in water work?

Answer 24

When an object is submerged in water, the liquid pressure under the objetc is greater than the pressure over it. So, the object is pushed upwards because the depth of the lower side is higher than the upper side.

Question 25

define Stress

Answer 25

A measure of how much force exerted over an area.

Question 26

Write the equation to calculate stress

Answer 26

Force (N) / Surface area (m2) = Stress (N/m2)