Forces Flashcards
What is a scalar force?
A scalar has a size (magnitude) and no direction. E.g speed
What is a vector?
Vectors have both size and direction. E.g velocity
Give a couple of examples of contact forces.
Air resistance and friction
Give a couple of examples of non-contact forces?
Gravitational forces and magnetic forces.
What is the link between weight and mass?
Weight and mass are proportional, whenever weight goes up (for example double) mass will also go up (by double in this case)
What is defined as the centre of mass?
The centre of mass is defined as where an object’s weight acts.
What is a resultant force?
A resultant force is when a single force can replace all the other forces acting on something (due its larger size)
What happens when an object is moved against a force?
work is done on it.
What is work done measured in?
Jules (J)
What is force measured in?
Newtons (N)
What is distance measured in
Meters (m)
What is extension measured in?
M (meters)
What is the relationship between force and extension? When does this relationship cease?
Force and extension are proportional unless you go past the limit of proportionality. There is a linear relationship up until this point.
What is elastic deformation?
When you take the force off the spring and it returns to its original length.
What is inelastic deformation?
When you apply too much force and when you take it off the spring and it does not return to its original length.
When a force is applied to a spring, what will happen to it and what energy will it have?
When a force is applied to the spring it will extend and change shape, it will have elastic potential energy stored.
What is elastic potential energy?
Elastic potential energy is energy stored in a system when work is done to change its shape.
What is the difference between distance and displacement?
Distance is how far you have gone. Displacement is how you are from one point and can be a positive or a negative.
What is the speed of sound in air and how can this very with different materials?
The speed of sound in air is around 330m/s. The more dense a material is, the faster it will take for sound it travel in it, e.g sound moves much faster in iron or brick or even water than air.
What is speed measured in?
Meters per second (m/s)
What does it mean when there is a straight line on a distance time graph?
A straight line means that the speed is constant (even when stationary).
What is acceleration measured in?
Meters per second squared (m/s^2)
What does it mean when there is a straight line going downwards on a velocity-time graph?
The straight line means that the object is going in a constant speed, but because it is going downwards it means that it will be negative.
What is terminal velocity? What happens once you reach it?
When the forces are balanced so the speed becomes constant. When you reach terminal velocity you cannot go any faster in the position.
What is Newton’s first law of motion?
A body will remain at rest or will continue at a constant velocity if no resultant force acts, e.g when a resultant force acts forwards on a car it will accelerate.
What is inertia?
Without an unbalanced force while moving at a constant velocity you would continue to move at a constant velocity, this is called inertia.
What is Newton’s second law of motion?
The acceleration of a body is proportional to the resultant force causing it to accelerate. It is inversely proportional to the mass of the object.
What is inertia mass a measure of?
Inertia mass is a measure of how difficult it is to change the velocity of an object
What is Newton’s third law of motion?
When body A exerts a force on body B, body B exerts an equal and opposite force on body A, e.g when you row a canoe the force you apply to the top of the paddle forwards will also be applied to the the water backwards causing you to move.
What is stopping distance?
Thinking distance (reaction time) + Braking distance (the time it takes for you to do the action).
What are some things that can affect someone’s time to think (their thinking distance)?
Drugs, alcohol, tiredness, poor visibility and their speed.
What is momentum made up of?
Any object with both mass and velocity has momentum.
What is a normal contact force?
When two objects are physically touching, e.g lamp on a table, a lamp is exerting a downward force on the table and the table exerts an upward force on the lamp
What is the centre of mass?
the weight of an object which acts at one point
Whats the difference between mass and weight?
Your mass stays the same everywhere but your weight depends on your GPE/ gravitational field strength
What’s a typical walking speed?
1.5m/s
What’s a typical running speed?
3m/s
What’s a typical cycling speed?
6m/s
