Flashcards in FM1 - Forces and friction Deck (17):
What is a force?
A push or a pull
Where does the force of gravity and weight act?
Where does a reaction force from a surface act?
Where does electrostatic forces act?
Between two charged objects - direction depends on type of charge
Where does thrust (push/pull) act?
When something is speeding up
Where do drag/air resistance/friction do?
Slow down objects
How can lift be caused?
Due to an aeroplane wing
How can tension be causes?
Due to a rope or cable
What are the opposite forces for the ones acting on our body;
- Reaction = gravity
- Thrust = Drag
What does friction oppose?
Motion - if an object has no force moving it, friction always slows it down
If you travel at a steady speed, what always need to counteract friction?
A driving force
What are the three ways that friction can occur?
- Friction between solid surfaces which are gripping
- Friction between solid surfaces sliding last each other
- Resistance from fluids (liquids or gases)
How can you reduce friction when solid objects are gripping or sliding past each other?
Put lubricants like oil or grease between the two surfaces to prevent the wear of the two surfaces in contact
How can you reduce resistance from fluids eg air?
Keep objects streamlined like sports cars or put deflectors on them like what lorries and caravans have
What spoils the streamlined shape on cars?
For a given thrust, the higher the drag...
The lower the top speed of a car - opposite to this is s parachute