Topic 9- Forces and their effects

Question 1

How can objects interect?

Answer 1

-Non contact fields
-Contact forces

Question 2

What is a non contact force?

Answer 2

-Occurs in a field
-Objects are not physically touching
-E.g gravitational or electrostatic or magnetic

Question 3

What are contact forces and what are two types?

Answer 3

-Physically touch:
-Normal contact force at 90 degrees
-Friction

Question 4

Where does the reaction force act?

Answer 4

Perpendicular to the surface (90 degrees)

Question 5

Which way does friction act?

Answer 5

Opposite to the direction

Question 6

Vector vs Scalar

Answer 6

-Both magnitude
-Vector has direction

Question 7

Vector examples? x5

Answer 7

-Displacement
-Velocity
-Force
-Acceloratiton
-Momentum

Question 8

Scalar examples? x5

Answer 8

-Energy
-Speed
-Disance
-Mass
-Temperature

Question 9

VECTOR DIAGRAMS? what are they?

Answer 9

-Draw all forces on eachother from new direction + proportional length
-Draw final line (start to finish)= resultant force
-Find angle of resultant force to first movement

Question 10

What do resultant forces have? on a vector diagram?

Answer 10

horizontal + verticle componenants

Question 11

What does a free body diagram show?

Answer 11

-All the forces that are acting on an object
-Using force angles (diff sizes)

Question 12

What are the 4 arrows ona free body diagram called?

Answer 12

-Lift vs Weight
-Thrust vs Drag

Question 13

What if resultant force is 0?

Answer 13

-Balanced, at equilibrium
-Will no longer accelerate
-Will contue its movement

Question 14

When do forces cuase rotation?

Answer 14

-When there is a moment or pivot
-E.g child on a seewsaw or using a hammer

Question 15

What is a moment?

Answer 15

The turning effect of a force around a pivot

Question 16

How do we work out the moment?

Answer 16

Force x perpendicular distance (from the moment to force)

Question 17

What is the principial of moments?

Answer 17

-Equilibrium + balanced
-Sum of clockwise vs anticlockwise moment
-Are the same

Question 18

When is the moment at equilibrium?

Answer 18

anticlockwise moment= clockwise moment

Question 19

What does a lever do?

Answer 19

-Transmits the turning effect of a force
e.g we apply an input force, it applies an output force

Question 20

If input and output force are on opposite sides of the pivot what happens?

Answer 20

Act in different directions e.g scissors

Question 21

If input and output force are on the same sides of the pivot what happens?

Answer 21

Act in the same direction e.g wheelbarrow

2nd and 3rd class

Question 22

How does the lever cuase a larger force?

Answer 22

-Allows effort to be further from pivot
- e.g transmits force for distance

Question 23

What does a gear do?

Answer 23

Transmits the turning effects
e.g the gears allows the turning effect of the engine to be transmitted to the wheel

Question 24

What happens if gears are interlocking?

Answer 24

-cuases the other gear to move
-In the opposite direction

Question 25

How do different radius' effect the gears rotation?

Answer 25

-A larger radius means a **larger turning effect** (per turn) -Other gears will rotate in proportion to their radius e.g 2x smaller gear will rotate twice for every one rotation of the bigger gear

Question 26

What is the difference workdone of two gears with different radius'?

Answer 26

-The same -One rotates more but has a smaller turning effect -Other rotates less but has a larger turning effect

Question 27

How to reduce unwanted energy loss? | friction

Answer 27

**Lubrication** reduces friction and therefore reduces heat loss and increases efficiency

Question 28

What is the fuclrum?

Answer 28

A pivot

Question 29

What is the first class lever?

Answer 29

-The **fulcrum** (pivot) is in the middle e.g seesaw | between load and effort

Question 30

What is the second class lever?

Answer 30

-The load is in the middle e.g wheelbarrow | between fulcrum and effort

Question 31

What is the third class lever?

Answer 31

-The effort (force) is in the middle -e.g tweezers | Between load and fulcrum