Physics - Forces, Newton's Laws, Energy and Power Flashcards
(33 cards)
What is a scalar quantity?
A physical quantity that has magnitude, but not direction.
What is a vector quantity?
A physical quantity having magnitude & direction.
What changes can force make to an object?
Forces can change the shape, speed and direction of an object.
What is weight?
The gravitational force of attraction between masses.
What is electrostatic force?
Force between electrically charged objects.
What is magnetic force?
The force between magnetised / magnetic objects.
What is friction?
The force that opposes movement between solids / fluids.
What is reaction force?
The normal contact between solid objects.
What is buoyancy / upthrust?
The force supporting a body floating in a fluid.
What is tension?
The pulling force transmitted by a string.
What is thrust?
The force intended to drive an object in a given direction.
Is force a scalar or vector quantity?
A vector quantity.
What is the resultant force?
The resultant force is the single force that has the same effect as all the individual forces acting together.
Resultant force (F) =
mass (m) x acceleration (a).
Weight (W) =
mass (m) x gravitational field strength (g).
What force acts on falling objects?
Air resistance.
What factors affect air resistance?
- The larger the surface area, the larger the air resistance.
- The larger the velocity, the larger the air resistance.
Explain why falling objects reach terminal velocity.
- When an object falls, its weight causes it to accelerate towards the ground.
- Restive forces act on it in the opposite direction to its motion.
- As the object’s speed increases, the restive force increases until these balance the downward force of the object’s weight.
- This means that there is no resultant force and it travels at a constant (terminal) velocity.
Stopping distance =
Thinking distance + braking time.
What factors affect vehicle stopping distance?
The mass of the vehicle. The speed of the vehicle. Road conditions e.g. wet roads. Reaction time which can be slowed by alcohol consumption.
What does proportional mean in a directly proportional relationship?
As one variable increases, the other variable increases at the same rate.
What is elastic behaviour?
Elastic behavior is the ability for a material to recover its original shape after the forces causing deformation have been removed.
What is elastic deformation?
Elastic deformation occurs when an object has been stretched and it returns to its original length after the forces have been removed.
What is inelastic deformation?
Inelastic deformation is when an object has been stretched and it doesn’t return back to its original length when the forces are removed. The object remains permanently stretched.
