Make sure you are familiar with units for
Mass: kilogram (kg)
Distance: metre (m)
Speed: metre per second (m/s)
Acceleration: metre per second squared (m/s^2)
Force: newton (N)
Time: second (s)
Gravity: newton/kilogram (N/kg)
A distance time graph has distance on the y axis (usually in metres) and time on the x axis (usually in seconds). The gradient of the line (change in y/ change in x) is the speed. If the line is flat then the object is stationary.
on a velocity time graph the velocity-time graph the velocity is on the y axis (usually in m/s) and time is on the x axis (usually in s). If the line is flat then the object is moving at a constant velocity. the gradient of the line is the acceleration. The area under the line is the distance travelled.
Gradient = acceleration= change in y/ change in x = change in velocity/time
The area under the graph can be calculated as rectangles and triangles, or by counting boxes, is equal to the distance travelled.
v2=u2+2as
v= final speed
u= initial speed
a= acceleration
s= distance moved
see all the rearrangements of this equation.
Forces can act on a body to change the velocity, so the speed, direction or both.
Or forces can change the shape of a body, stretching it squishing it or twisting it.
different types of forces include:
Gravitational, weight, friction, electrostatic, air resistance (drag), tension (force in a spring), up thrust, lift, thrust
scalars are quantities with only magnitude (size)
vectors are quantities with magnitude (size) and direction
Force has a magnitude measured in (N) but it also has a direction, a push or a pull, up, down, left or right. So force is a vector.
Forces along a line can combine by addition.
Force = Mass x Acceleration.
the force refers to the resultant force or the combined forces as seen in 1.15
Initially the only force is weight as drag is proportional to velocity. So the object accelerates downwards. As it accelerates the velocity so the drag increases as well. meaning there is a smaller resultant force downwards so a smaller acceleration. Until the object reaches a speed where the drag is equal to the weight meaning there is no acceleration, this velocity is know as terminal velocity.
Hooke’s law is that extension is directly proportional to force applied. This is shown by the straight line on the force-extension graph. Hooke’s law is obeyed as long as the line is straight.
Elastic behaviour is the ability of a material to recover original shape after the force is removed. in a spring this occurs when the force is lower than the elastic limit. loading and unloading force extension curves can be different as long as it returns to its original shape.
