Motion
When calculating the distance from a graph don’t forget the area below the
triangle
Forces
F =ma
Every action produces an equal and opposite force reaction
Vehicles will reach their top speed when the forward force equals the
drag force. Vehicles that are more streamlined have a smaller drag force
so their drag force will equal the forward force at a higher speed.
All cars have a top speed because as the speed increases, so does the size
of the drag force so eventually the drag force becomes equal to the thrust.
Thus the resultant force is now 0 and there is no further acceleration.
Cyclist = Forward force is greater than frictional force/air resistance so
cyclist accelerates and velocity increases. However, as cyclist moves
forward, air resistance increases so resultant force decreases. Cyclist
continues to accelerate at a smaller rate until air resistance increases till
air resistance equals the forward force and the resultant force is 0.
Acceleration also is 0 as the cyclist now travels at terminal velocity.
Parachutist = on leaving the plane the only force acting is gravity. As the
parachutist falls, air resistance acts but the resultant force is still
downwards, so the parachutist accelerates. As his velocity increases, so
does air resistance and finally terminal velocity reached when the forces
are balanced.
o Then as he parachute is opened, the surface area increases, which
increases air resistance. As air resistance is greater than weight,
the resultant force is upwards. This means the parachutist slows
down and the lower velocity means a reduced air resistance. This
means air resistance become equal but at a lower terminal
velocity.
Thinking distance = distance vehicle travels during the driver’s reaction
time. It is affected by tiredness, alcohol or drug consumption and
distractions like mobile phones.
Braking distance is affected by the speed of the car, braking force, tyre
conditions, and icy/wet roads…
Braking distance = the distance a vehicle will travel from the point the
brakes are applied till it stops
Braking means the work done by friction causes a decrease in KE and
increase in heat energy
Regenerative batteries are good because the battery needs less
recharging as the efficiency of the car is increased because not all the
work done is wasted.
Work, Energy and Momentum
Elastic potential energy is stored in the stretched spring (N/m)
Work done is measured in joules / power = watts
When calculating the distance from a graph don’t forget the area below the
triangle
Forces
F =ma
Every action produces an equal and opposite force reaction
Vehicles will reach their top speed when the forward force equals the
drag force. Vehicles that are more streamlined have a smaller drag force
so their drag force will equal the forward force at a higher speed.
All cars have a top speed because as the speed increases, so does the size
of the drag force so eventually the drag force becomes equal to the thrust.
Thus the resultant force is now 0 and there is no further acceleration.
Cyclist = Forward force is greater than frictional force/air resistance so
cyclist accelerates and velocity increases. However, as cyclist moves
forward, air resistance increases so resultant force decreases. Cyclist
continues to accelerate at a smaller rate until air resistance increases till
air resistance equals the forward force and the resultant force is 0.
Acceleration also is 0 as the cyclist now travels at terminal velocity.
Parachutist = on leaving the plane the only force acting is gravity. As the
parachutist falls, air resistance acts but the resultant force is still
downwards, so the parachutist accelerates. As his velocity increases, so
does air resistance and finally terminal velocity reached when the forces
are balanced.
o Then as he parachute is opened, the surface area increases, which
increases air resistance. As air resistance is greater than weight,
the resultant force is upwards. This means the parachutist slows
down and the lower velocity means a reduced air resistance. This
means air resistance become equal but at a lower terminal
velocity.
Thinking distance = distance vehicle travels during the driver’s reaction
time. It is affected by tiredness, alcohol or drug consumption and
distractions like mobile phones.
Braking distance is affected by the speed of the car, braking force, tyre
conditions, and icy/wet roads…
Braking distance = the distance a vehicle will travel from the point the
brakes are applied till it stops
Braking means the work done by friction causes a decrease in KE and
increase in heat energy
Regenerative batteries are good because the battery needs less
recharging as the efficiency of the car is increased because not all the
work done is wasted.
Work, Energy and Momentum
Elastic potential energy is stored in the stretched spring (N/m)
Work done is measured in joules / power = watts
