Feed-up: forces

force

anything that changes the speed, shape, size or direction of an object.

name an instrument used to measure force

newton meter/ spring balance

What effect will balanced forces have on the velocity of an object

the object will remain at the same velocity

what effect will unbalanced forces have on a body

the object will accelerate

three effects that a force can have on a body

change in velocity, change in shape, change in direction

what is friction

friction is a force that opposes motion between two surfaces

advantages of friction

• allows brakes to be used

• helps you to move

• slows down rain and hailstones

disadvantages of friction

• slows things down

• wastes energy

• causes wear

3 ways of reducing friction

• lubrication

• ball bearings

• streamlining

what is weight?

the measure of the force of gravity on a body

calculations to find weight

weight = mass of object in kilograms x g value at the location

what is the unit of force

newton (N)

how mass differs from weight

• the amount of matter in a substance

• remains constant everywhere in the universe

• can never be 0 for an object

• unit = kg

how weight differs from mass

• the measure of the force of gravity on a body

• depends on the amount of gravity in a location

• can be 0 if no gravity is present

• unit = newton

hooke’s law experiment

1. set up the apparatus as shown. hang the spiral spring from the retort stand. hang the weight holder from the bottom of the spring.

2. in a separate clamp, clamp the metre stick so that it is vertical and parallel to the spring

3. Note the number measured on the metre stick at the bottom of the spring with no force applied.

4. add a weight to the weight holder. note the number that the spring has extended to.

5. add more weights to the weight holder, noting the weight added and the extension every time.

6. graph the weight and extension to prove hooke’s law

hooke’s law

is a scientific law that states that the extension of a spiral spring is directly proportional to the force applied

non-contact force

a force that can act on an object without touching it physically

contact force

any force that occurs because of two objects making contact with eachother

non contact forces:

• magnetism

• electrostatic force

• gravity

contact forces

• pull

• push

• twist/turn

• friction

• tension and surface tension

• support forces