P1: Forces
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All forces are measured in…
Newtons (N)
List some examples of contact forces.
Friction Air resistance Reaction force Upthrust
What is a force?
A push or a pull
The force of water pushing a boat up is called…
upthrust
A force that acts without touching is called a…
Non-contact force.
What do we use to measure a force?
Newtonmeter (force meter)
What 3 effects can forces have on objects?
Change their shape (deform). Change the direction the object moves in. Change their speed (accelerate/ decelerate).
What do we call forces that act when you touch something?
A contact force.
List 3 non-contact forces.
Gravity Magnetism Electrostatic force
Explain how the reaction force works.
• The floor is a solid and made from particles. • Your weight pushed the particles together. • The bonds holding the particles together are compressed. • They push back to support you.
If you double the force on a spring you will _________ the extension (stretch) of the spring.
double
When a stetched string pulls back we call it…
tension
The force of the Earth pushing an upject up is called the…
reaction force.
The amount that a spring can stretch is called its…
extension
If you stretch a spring so long that it can no longer go back to its original size we say that the spring has reached its…
elastic limit
What is the scientific word for ‘squash’?
Compress
“The stretch of a spring is diectly proportional to the force applied, providing the elastic limit has not been reached”. This is called …….
Hooke’s Law
Rough surfaces have ______ friction.
more
What is friction?
A force that acts when two force against each other. Friction causes grip.
Smooth surfaces have _______ friciton.
less
How can you reduce drag forces?
Have a streamlined shape.
Name the two drag forces.
Air resistance Water resistance
How can you reduce friction between 2 surfaces?
Use lubrication e.g. oil
When is friction a good thing?
Friction between your shoe and road to allow you to walk. Friction between bike/car brakes and the wheels to allow you to stop.