Forces Flashcards
What do scalar quantities have?
MAGNITUDE (size) only. DO NOT have a DIRECTION.
Give 3 examples of scalar quantities.
Any 3 from: mass, temperature, speed, energy, distance and time
What do vector quantities have?
MAGNITUDE and DIRECTION.
Give 3 examples of vector quantities.
Any 3 from: displacement, weight, force, velocity, acceleration and momentum.
What two categories can forces be divided into?
Contact forces and non-contact forces.
What is a force?
A force is a PUSH or a PULL that acts on an object due to the INTERACTION with another object.
What is a contact force?
A contact force where TWO OBJECTS are PHYSICALLY TOUCHING.
Give an example of a contact force.
Any 1 from: friction, tension and air resistance.
What is a non-contact force?
Where to the TWO OBJECTS are PHYSICALLY SEPARATED.
Give an example of a non-contact force.
Any 1 from: gravitational force, electrostatic force and magnetic force.
What is meant by mass?
The mass of an object tells us how much MATTER the object has IN IT.
What is meant by weight?
The weight of an object is the FORCE acting on it due to GRAVITY.
What equation do you use to calculate weight?
weight (N) = mass (kg) x gravitational field strength (N/kg) W = m g
What can we say about weight and mass of an object?
The weight of an object is DIRECTLY PROPORTIONAL to the mass of the object. Weight ∝ Mass
What is meant by gravitational field strength?
It is a measure of the force of GRAVITY in a particular LOCATION.
What is meant by altitude?
HEIGHT above the ground.
What is key about inelastic material?
They DO NOT return to their original length when the forces are removed (INELASTIC DEFORMATION).
What equation do we use to calculate the force needed to stretch an elastic object?
Force (N) = spring constant (N/m) x extension (m)
What equation do we use to calculate speed?
speed (m/s) = distance / time
What does the gradient of a distance time graph tell us?
Tells us the object’s SPEED.
How do you work out the gradient?
gradient = distance travelled / time taken
What equation do we use to calculate acceleration?
………………………….2
acceleration (m/s) = change in velocity (m/s) / time (s)
What does the gradient of a velocity time graph tell us?
The ACCELERATION of the object.
What does a horizontal line show us?
That the object is travelling at a CONSTANT VELOCITY.
What does an upward sloping line tell us?
That the object is ACCELERATING.
What does a downward sloping line tell us?
That the object is DECELERATING.
What does the total area under the graph tell us?
The DISTANCE TRAVELLED in a specific direction (displacement).
What is key about Newton’s First Law of Motion in relation to resultant force?
The VELOCITY of an abject will only change if a RESULTANT FORCE is acting on the object.
What is Newton’s second law of motion?
The ACCELERATION of an object is PROPORTIONAL to the RESULTANT FORCE acting on the object and INVERSELY PROPORTIONAL to the MASS of the object.
What is Newton’s third law of motion?
Whenever two objects interact, the FORCES they exert on each other are EQUAL and OPPOSITE.
What is meant by the stopping distance?
Is the total DISTANCE travelled from when the driver first spots the obstruction to when the car stops.
What is meant by the thinking distance?
The distance travelled by the car during the driver’s REACTION TIME.
What is meant by the reaction time?
The time taken for the driver to spot the obstruction, make a decision and then move their foot to the brake.
What is meant by the breaking distance?
It is the distance the car travels from when the driver APPLIES THE BRAKES to when the car STOPS.
What is the stopping distance made up of?
The THINKING DISTANCE plus the BRAKING DISTANCE.
What happens when we double the velocity of the car?
The KINETIC ENERGY QUADRUPLES.
What momentum do non moving objects have?
NO MOMENTUM.
What equation do we use to calculate momentum?
momentum (kg m/s) = mass (kg) x velocity (m/s)
What is the conservation of momentum?
In a closed system, the total momentum BEFORE an event is equal to the total momentum AFTER an event.
What does unifrom mean?
When ab object’s speed (velocity) is increasing at a constant rate.
Label the following on a distance-time graph: Steady speed, stopped, accelerating and decelerating.
What does the gradient equal on a distance-time graph?
Gradient = speed (The steeper the graph, the faster the object is going.)
This is because: speed = distance / time = (change in vertical axis) / (change in horizontal axis).
Label the following on a velocity-time graph: constant acceleration, steady speed, increasing acceleration, steady speed and constant deceleraion.
What does the gradient equal on a velocity-time graph?
Gradient = acceleraion, since acceleration is change in velocity / time.
