Physics
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What is a force
Pushes or pulls that occur when 2 objects interact- can’t be seen but effect can be seen
What are forces measured in
Newtons - N
What can you use to measure force
Newton meter
Name 5 things forces can make an object do
Speed up - eg kicking a football Slow down eg air resistance Change direction Turn eg turning a spanner Change shape eg stretching and compression
Forces can be balanced and ……
Unbalanced
Balanced forces create no change of movement .true or false
True eg bus moving at a steady speed in the same direction -there is movement but forces are balanced
Unbalanced forces change the speed or direction of an object- true or false
True eg motor boat accelerating -force from motor boat is greater than the resistance from the water so the boat speeds up
Name 2 types of frictional force
Friction and air resistance Friction acts between 2 surfaces eg tyre on a road Air resistance is drag which pushes against objects moving through the air
How does a parachute help you slow down
When a parachute opens air resistance increases as there is a larger area trying to cut through the air
A sheep with a parachute on moves at a steady speed through the air- why
At this point the air resistance is equal to the weight of the sheep - the forces are balanced so they move at a steady speed
What is the formulae for extension of a spring
Extension =position with weight -position without weight Eg spring on a clamp without weight is 2 cm and once you add the weight it’s 10 cm SO EXTENSION IF THE SPRING = 10-2 =8CM
What is the formula for compression
Compression = position without weight -position with weight
What is mass measured in
Kg
What is the weight formula
Weight = mass (kg) x gravitational field strength (N/kg) Weight in newtons of a 5kg mass on earth ? On earth gravitational field strength is 10 N/kg so Weight = 5 x 10 = 50 N
What is the formula for speed
Speed = Distance ——————— Time Remember SIDOT- SPEED IS Distance over time
What are the 3 common units for speed
Metres per second =m/s Miles per hour - mph Kilometres per hour= km/h
What factors affect your stopping distances
How fast you are going The faster you are going the longer it will take to stop
What is the formula for stopping distance
Stopping distance = thinking distance + braking distance
What is thinking distance
The distance the vehicle travels during the drivers reaction time
What is braking distance
The distance the car travels under the braking force
What factors affect braking distance
How fast you are going How good your brakes are How good your tyres are How good the grip is eg road surface \weather/tyres
Magnetic field lines always point from ———— to ————-
North to south
Unlike poles———-
attract - so North Pole of a magnet attract the South Pole of a magnet
Like poles ———-
Repel North Pole of a magnet will repel - push away from the other north pole