science unit 1

Question 1

what is a force?

Answer 1

a push or pull

Question 2

what are the effects of forces?

Answer 2

Start an object moving
Stop a moving object
Change the speed of a moving object
Change the direction of a moving object
Change the size & shape of an object
Bring about turning effects in objects

Question 3

SI unit of force?

Answer 3

Newton (N)

Question 4

effects of friction

Answer 4

Opposes movement of an object
Causes surfaces to heat up
Better grip
Makes movement more difficult
Wears away materials

Question 5

how to reduce friction

Answer 5

Use smooth surfaces
Ball bearings (prevents wearing out)
Lubricants (grease/oil)
Streamlining
Layer of air between surfaces

Question 6

weight

Answer 6

Measure of force of gravity exerted on an object
The heavier an object, the greater the force acting on it
Measured using a spring balance (weight is a force)
Weight= mass(kg) x 10

Question 7

what is pressure

Answer 7

The measure of the amount of force acting on a unit area

2 factors: force & area

Question 8

increasing pressure

Answer 8

Reduce area

For the same force, the pressure exerted on an object is higher when a smaller surface is in contact with the object

Question 9

reducing pressure

Answer 9

Increase area
Needed when people/machines move on soft ground
When a larger surface is in contact with the ground, the pressure exerted on the ground is lower so people/machines can move without sinking

Question 10

calculating pressure

Answer 10

Pressure = force/area
Unit of pressure: newton per square meter (N/M2) or pascal (Pa) [SI unit of pressure: Pa]
1Pa=1N/M2