P1 - Motion Flashcards
What six measurements are scalar quantities?
temperature
mass
energy
distance
speed
density
What five measurements are vector quantities?
force
displacement
velocity
acceleration
momentum
What is a force?
A push, pull, or twist that can change something about an object.
How does a force affect things?
It can change the object’s speed, direction or shape.
What are the six contact forces?
Applied force
Normal force
Friction force
Air resistance force
Tension force
Spring force
What are the three non-contact forces?
Gravitational force
Magnetic force
Electrical force
What are the two types of friction?
Static and Dynamic.
How do you calculate the distance from a speed-time graph?
Measure the area under the graph.
How do you calculate the acceleration from a speed-time graph?
Measure the gradient (slope) at that point.
What is friction?
It resists (opposes) motion (two things in contact moving past each other), it acts in the opposite direction; kinetic energy is transferred to thermal (heat) energy (by mechanical transfer).
What is Newton’s first law of motion?
An object stays at rest or continues to move at a constant speed in a straight line unless a net force acts on it.
What is inertia?
Inertia is a body’s (object) resistance to change its speed (stationary speed=0) and/or its direction.
What is Newton’s 3rd law of motion?
For every action there is an equal and opposite reaction.
What is Newton’s 2nd law of motion?
When an object is at rest (stationary) or moving with constant speed the forces are balanced.
What is the formula for force?
Force = Mass x Acceleration
What are the units for force?
Newtons.
What is the formula for speed?
Speed = Distance/Time
What is the formula for acceleration?
Acceleration = Change in velocity/Time
What is the other formula for acceleration that involves force?
Acceleration = Force/Mass
What is an elastic object?
An elastic object is something that will return to its original shape when the forces deforming it are removed.
What is Hooke’s law?
The amount a spring stretches is proportional to the amount of force applied to it.
What is the spring constant?
The spring constant measures how stiff the spring is. The larger the spring constant the stiffer the spring.
What is Hooke’s law as an equation?
Applied force = Spring constant x extension
N = N/m x m
What is a moment?
The turning effect of a force.
What is it called when something turns to the right?
Clockwise.
What is it called when something turns to the left?
Anti-clockwise.
What is the formula for a moment?
Moment = Force x Distance (from the pivot)
How do calculate multiple moments together?
If they are all clockwise or anti-clockwise then add them together. If they are different, bigger moment - smaller moment.
What is equilibrium?
if the clockwise moment is equal to the anticlockwise moment.
What is another name for a pivot?
Fulcrum.
What is another name for force?
Effort.
What things have mass?
All things.
What is the centre of gravity?
An object behaves as if its whole mass were concentrated at ONE point.
How do you find the centre of gravity of a symmetrical object?
When you draw lines (axis) of symmetry for a regular object all the lines will cross at one point.
This is the centre of gravity for that object.
How do you find the centre of gravity for an irregularly shaped object?
- Place at least three holes around the edge of the card and hang it up from a pin and let it swing freely.
- When you do this, the centre of mass of the card is directly below the pin.
- You can use a ‘plumb line’ to draw a vertical line on the card from the pin downwards.
- Now repeat this procedure with the card suspended from the other holes to give some more lines.
- The centre of mass of the card is where the two lines meet.
What are the 3 types of equilibrium?
Stable equilibrium, unstable equilibrium, neutral equilibrium.
What is stable equilibrium?
After a small displacement the body returns to its original equilibrium position.
What is unstable equilibrium?
After a small displacement the body does not return to the original equilibrium position and moves to a new equilibrium position.
What is neutral equilibrium?
After a displacement, the body remains in the displaced position.
How do you make an object more stable?
Increase the base.
What is weight?
The effect of a gravitational field acting on a mass.
What do we use to measure mass?
Top-pan balance.
What is the equation for pressure?
Pressure = Force/Area
