L1 Mechanics - physics Flashcards
First Law of conservation
Energy cannot be created nor destroyed, only converted from one form to another
Newton’s first law of motion
Unless a force is applied, an object will stay at rest or stay at a constant velocity
Newton’s second law of motion
A force applied on an object causes an acceleration in the same direction as the force and this acceleration is equivalent to the amount of force over the mass of the object
Acceleration
The rate of change in velocity, the change in velocity over the change in time.
a= v/t
What is the unit for acceleration?
ms-2
Deceleration
Can be described as negative acceleration, decrease in velocity over time.
What is the unit for deceleration?
Meter per second square
m/s2
Energy
The ability to do work
Unit of energy
Joules
Force
The interaction that changes the motion of an object. The push or pull on an object.
Fnet = ma
What is the unit for force?
Newtons (N)
Power
The rate of doing work
P= W/t (don’t get this confused with pressure)
What is the unit for power?
Watts (W)
Pressure
The physical force exerted on an object OR force applied over an area
P= F/A (don’t get this confused with power)
What is the unit for pressure?
Pascals (Pa)
Velocity
The rate of change in distance, speed in a given direction
v = d/t
What is the unit for velocity?
m/s
Speed
Speed is the time rate at which an object is moving along a path
What is the unit of speed?
ms-1
Difference between speed and velocity
Velocity is the rate at which an object changes its position
Speed is simply how fast an object is moving
Joules (J)
What is the unit for work?
Seconds (s)
What is the unit for time?
Seconds (s)
What is the unit for distance?
Metres (m)
What is the unit for area?
Meters squared (m2)
What is the unit for height?
Meters (m)
Weight
The force acting on the object
F=mg
What is the unit of weight?
Newtons (N)
Mass
Amount of matter in an object
Whats is the unit for mass?
Kilograms (Kg)
Difference between mass and weight
Mass is a measure of how much matter there is in an object whereas, weight is the measure of the pull of gravity on the object
Friction
The force that acts in the opposite direction of the object in motion.
Kinetic Energy
The energy of an object due to its motion
e.g moving car
Gravitational Potential Energy
Energy stored in an object due to its height
e.g car that is parked on top of a hill
Chemical Potential Energy
The energy that is stored in the bonds between atoms.
e.g batteries
Light Energy
The energy of electromagnetic waves
e.g flashlight
Heat Energy
Transfer of energy from one thing to another by kinetic energy, usually causing a higher temperature
e.g stove
Electrical Energy
The movement of electrically charged particles
Elastic Potential energy
Energy stored in stretched or squashed objects
Magnetic energy
The energy created by the strength of a magnetic field
e.g refrigerator
Distance-time graph
Use gradient for calculating speed
Distance-time graph
Used to show how the distance and speed of an object changed with time
What does a horizontal (flat) line in a distance-time graph indicate?
Stationary/stopped
- Object has no acceleration and therefore no net force
What does a straight line heading upwards on a distance-time graph indicate?
Constant speed
- Object has no acceleration and therefore no net force
What does a curved line on a distance-time graph indicate?
Accelerating
- Object is changing speed which means it is acceleration/decelerating therefore resulting in a net force
Speed-time graph
Used to describe the movement of an object
What does the area under a speed-time graph show?
Distance traveled
How do you use gradient in a speed-time graph?
Use gradient for calculating speed/acceleration
What does a horizontal (flat) line in a speed-time graph indicate?
Constant speed
- Object has no acceleration and therefore no net force
What does a straight line going down in a speed-time graph indicate?
Constant deceleration
- Non-constant speed, the object is changing speed so it is accelerating/decelerating therefore resulting in a net force
Area
The area under the graph shows distance traveled
Balanced forces
The forces acting on an object are the same size
Unbalanced forces
The forces acting on an object are not the same size
What is work done equal to?
Energy transferred
What are the four forces acting on an object?
Friction/air resistance
Weight/gravity
Thrust
Support force
What is the force that pulls an object down?
Weight/gravity
What is the force that pulls an object up?
Support force
What is the force that pulls an object forward?
Thrust
What is the force that pulls an object backward?
Friction/air resistance
