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What is a force?
A push or pull that acts on an object due to the interaction with another object.
What are forces measured in?
Newtons (N).
What can forces make an object do?
Change the speed, change the direction, change the shape.
What is a contact force?
When the objects are physically touching.
What is a non-contact force?
When the objects are physically separated.
Examples of contact forces include:
Friction, tension, air resistance, normal contact force, lift.
Examples of non-contact forces include:
Magnetic force, electrostatic force, gravity.
What are scalar quantities?
They have magnitude only (size).
What are vector quantities?
They have magnitude and an associated direction.
Examples of scalar quantities include:
Mass, time, distance, temperature, energy, speed.
Examples of vector quantities include:
Velocity, acceleration, forces, displacement.
What is 1 kN equal to?
1000 N.
What is gravitational force?
The area around an object where another body experiences a force.
What is the difference between mass and weight?
Mass is measured in kilograms (kg); weight is measured in Newtons (N).
Are mass and weight directly or inversely proportional?
They are directly proportional.
What is mass?
The amount of matter in an object.
What is weight?
The effect of gravity on an object.
What is the gravitational field strength of the Earth?
9.8 N/kg.
What is the centre of mass?
When weight acts through a single point of an object.
What equation links gravitational field strength, weight, and mass?
Weight = mass x gravitational strength; w = m g.
What is a resultant force?
The sum of all forces acting on an object.
What happens to the resultant force when forces are balanced?
Resultant force equals zero; the effect is constant velocity or stationary.
What happens when forces are not balanced?
Resultant force does not equal zero; the effect is acceleration or deceleration.
If there is a resultant force, what will happen to the object?
The object will accelerate in the direction of that resultant force.
What is speed?
How fast an object moves.
What are the units for speed?
Metres per second (m/s).
What is acceleration?
The rate of change of velocity.
What is uniform acceleration?
When the acceleration is constant.
What is momentum?
The product of the mass and velocity of an object; p = m x v.
What is the principle of conservation of momentum?
The momentum in a closed system is always conserved.
What is a closed system?
A collection of objects that are not affected by external factors.
What happens in collisions regarding momentum?
The total momentum before equals the total momentum after.
What is inertia?
The tendency of objects to continue in their state of rest or uniform motion.
What does Newton's first law state?
An object at rest will remain at rest, and an object in motion will remain in motion unless acted on by a resultant force.
What does Newton's second law state?
The acceleration of an object is proportional to the resultant force acting on it and inversely proportional to its mass.
What does Newton's third law state?
Whenever two objects interact, the forces they exert on each other are equal and opposite.
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