Area under the graph shows total distance covered.
Force =
Mass x Acceleration
N - Newtons
Weight =
Mass x Gravity
N - Newtons
Mass
g, kg
Gravity
N/g, N/kg
Terminal Velocity
the constant maximum velocity reached by a body falling through the atmosphere under the attraction of gravity
Moment
Force x Perpendicular distance from pivot
Nm
Equilibrium
All forces and moments are balanced
Hooke's Law
Material obeys Hooke's Law if the force-extension graph is linear
Resultant force
All forces added together
Elastic
Object can recover original shape once a deforming force is removed
Speed, Distance and Time
Speed = Distance ÷ Time
m/s, km/hr, mph, Mach, knots, light speed
Time = Distance ÷ Speed
s, min, hr
Distance = Speed x Time
cm, m, km
How do you determine distance travelled from a velocity-time graph?
area under the graph
What are the effects of a force?
changes in speed, shape or direction
What is friction?
A force that opposes motion
Describe the forces acting on falling objects and explain why they reach terminal velocity.
When an object falls it will initially accelerate. The force caused by air resistance increases as the speed increases. Eventually air resistance will equal the force of gravity, the forces are balanced and the speed is constant (a.k.a. terminal velocity)
What does 'stopping distance' include?
thinking distance and braking distance
what factors affect thinking distance?
speed, tiredness, alcohol, medication, level of concentration
What factors affect braking distance?
speed, tyres, brakes, road conditions, mass of car
What is the centre of mass/gravity?
The point where all the mass of the object is concentrated.
moment =
force x distance
What is Hooke's law?
When a spring stretches, the extension of the spring is proportional to the force stretching it, provided the elastic limit of the spring is not exceeded.
What is elastic behaviour?
The ability of a material to recover its original shape after the forces causing deformation have been removed.
What do comets orbit?
The sun!
Describe the orbit of a comet.
A comet has an elliptical orbit that causes the speed to increase closer to the sun due to gravity (they can only be seen close to the sun).
How do planets orbit the sun?
Circular orbit
Displacement
The distance travelled in a specific direction.
Velocity
Speed in a specified direction. Measured in m/s/s.
Gradient
Slope which gives speed on a distance-time graph.
Straight lines
Lines that mean constant speed on a distance-time graph.
Area under the graph
Area which shows distance travelled on a velocity-time graph.
Define Weight
Weight is the force that acts on a body because of gravity. Measured in Newtons (N).
Friction
The force that opposes motion, either when you try to make something move or whilst it is moving.
Air resistance
Friction between an object and the air (or gas) that is moving through.
Upthrust
The upward force that liquids and gases exert on objects.
Magnetic
Forces that magnets exert on other magnets or things made of iron.
Electrostatic
The force between electrically charged objects.
Normal reaction
The special name for the contact force that acts on an object pressing down on another object.
Tension
In strings, cables, ropes, etc. that are being stretched.