P1.1 Forces Flashcards
What is a force?
A push or pull that can move objects
What is the unit of force?
Newton (N)
Forces always come in?
Pairs
How do you measure a force?
Newton meter
What is the main component of a newton meter?
A spring
What are balanced forces?
When you have equal opposite forces acting on an object
What happens to the motion of an object if it experiences balanced forces?
No acceleration (object does not speed up or slow down)
What happens to the motion of an object if it experiences unbalanced forces?
Accelerates (speeds up or slows down)
What is a contact force? Give examples
A force that acts when two objects are touching. Friction, air resistance, upthrust, reaction force.
What is a non contact force? Give examples
A force that acts when two objects are not touching. Gravity, magnetic force, electrostatic force.
What is a field?
A region where an object will experience a force
What is a reaction force?
A support force from an object
Why does a reaction force occur?
As the weight of an object pushes particles closer together, the bonds are compressed, they push back and support the weight of the object.
How can you reduce air resistance?
Streamline the objects, reduce it’s surface area
How can you increase air resistance?
Increase the surface area of the object
Can you give a useful example of friction?
Pencil on paper, friction between floor and your feet, car tyres and the road
Can you give an unuseful example of friction?
Between a bike chain and the wheel, slipping on ice
How can you reduce friction?
Use a lubricant
How do you calculate the extension of a spring?
New length - original length
What is Hooke’s Law?
When the extension of a spring doubles when you apply twice the force. (This gives a linear graph)
What is the elastic limit?
When you remove the force on a spring - the spring will not go back to it’s original length
What is the difference between mass and weight?
Mass does not change - it is the amount of matter an object is made of, weight is a force - it will change depending on location
What equation links mass and weight?
Weight = Mass x Gravitational Field Strength
What is the unit of weight?
Newton (N)
What is the unit of mass?
kilogram (kg)
What is the gravitational field strength on Earth?
around 10 N/kg
How can you calculate the gravitational field strength on any planet?
g = W / m (Weight divided by mass)