SP2a-e Motion & Forces Flashcards
What is a vector quantity
Have direction as well as magnitude
Vector quantity examples
- Force
- Weight
- Displacement
- Acceleration
- Velocity
What is a scalar quantity
Only has a magnitude
Examples of scalar quantities
- Speed
- Distance
- Mass
- Time
- Energy
What happens when an object changes its velocity?
It accelerates as acceleration is a change in a vector quantity.
Resultant force
The total amount of force acting on the object.
Balanced forces
If all the resultant forces on an object equal zero.
Unbalanced forces
If there is a non-zero resultant force on an object
What did Newton’s ‘laws’ describe?
How forces affect the movement of objects
What is Newton’s First Law
- A moving object will continue to move at the same speed and direction unless an external force acts on it.
- A stationary object will remain at rest unless an external force acts on it.
What is centripetal force in terms of velocity
The resultant force that causes the change in direction.
What is mass
The quantity of matter there is in an object, and only changes if the object itself changes. Measured in kilograms.
What is weight
The measure of the pull of gravity on an object and depends on the strength of gravity. It is a force measured in Newtons.
What is the gravitational field strength on earth?
10 (9.8) newtons per kilogram (N/kg)
How can weight be calculated?
Weight(N) = mass(kg) x GFS(N/kg)
What is Newtons Second Law
The factors that affect acceleration. The acceleration in the direction of a resultant force depends on:
* the size of the force (for the same mass, the bigger the force the bigger the acceleration)
* the mass of the object (for the same force, the more massive the object the smaller the acceleration).
How do you calculate force?
Force(N) = mass(kg) x acceleration(m/s_2)
Inertial mass
The more mass the object has, the more force is needed to accelerate it. It is defined as the force acting on it, divided by the acceleration produced by that force.
What is Newton’s Third Law
The forces on two different objects when they interact with each other. This interaction can happen:
* when objects touch, like when you sit on a chair.
* at a distance, like the gravitational attraction between the earth and the moon.
Action-reaction forces
Two forces that are always the same size, and same type of force but act in opposite directions.
What is an equilibrium situation
When nothing is moving
Examples of action reaction pairs
Force from the ground on you and force from you on the ground.
What is the difference between action reaction pairs and balanced forces.
In both cases the sizes of the forces are equal and act in opposite directions but:
* A-R forces act on different objects.
* Balanced forces all act on the same object.
How do objects affect each other
when they collide.
The A-R forces that occur during the collision are the same size, but they don’t necessarily have the same effect on the two objects, because the objects have different masses.
