Forces And Their Effects Flashcards
What are vectors
Vectors are quantities that have magnitude and an associated direction
What’s examples of scalars and displacement
Distance, speed and time
Examples of vectors
Displacement, acceleration, force and momentum
What can the distance an object loved in a straight line from a certain point be represented in
Distance time graph
What can speed be determined by in an distance time graph
The gradient
How do you determine the speed of an object accelerating at any particular time
By finding the gradient of the tangent of the distance time graph at that time
What is the velocity of an object
It’s speed in a given direction
Velocity, displacement , time taken word equation
Velocity = speed / time
Acceleration velocity and time taken word equation
Acceleration = (final velocity - initial velocity) / time taken
What can be determined by the gradient of a velocity time graph
The acceleration of an object
How do you find the distance travelled by an object on a velocity time graph
It can be determined from the area under a velocity time graph
What is the relationship between momentum mass and velocity
Momentum = mass x velocity
What is conservation of momentum
In a closed system the total momentum before an event is equal to the momentum after the event
Momentum is conserved whenever objects interact, as long as
The objects are in a closed system so that no external forces act on them
When two objects push each other apart, they move :
With different speeds if they have unequal masses With equal and opposite momentum, so their total momentum is zero
What does the force of the impact depend on when vehicles collide
When vehicles collide, the force of the impact depends on mass, change of velocity and the duration of the impact
When two vehicles collide
They exert equal and opposite forces on each other Their total momentum is unchanged
What is the relationship between force , change in momentum and time
Force = the difference in momentum / time
The longer the impact time,
The more the impact force is reduced
How do seat belts and air bags help protect you in car accidents
They spread the force across the chest and increase the impact time
What do side Impact bars and crumple zones do
They give way in an impact , so increasing the impact time
When a vehicle travels at a steady speed , the …….. Forces balance the ……….. Force
The resistive forces balance the driving force
The greater the speed of a vehicle,
The greater the braking force needed to stop it in a certain distance
For a given braking force , the greater the …… ,The greater the …..
For a given braking force, the greater the speed, the greater the stopping distance
What is the stopping distance of a vehicle
The stopping distance of a vehicle is the sum of the distance the vehicle travels during the drivers reaction time (thinking distance) and the distance it travels under the braking force (braking distance)
Wha can a drivers reaction time be affected by
Tiredness, drugs and alcohol (and other distractions)
What happens when the brakes of a vehicle are applied
Work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increases
What can a vehicles braking distance be affected by
Adverse roads and weather conditions and poor conditions of the vehicle
What are scalars
Scalars are quantities that have magnitude only
The faster an object moves through an object …
The greater the frictional force which acts on it
What happens to an object falling through a fluid
It will initially accelerate due to the force of gravity. Eventually the resultant force will be zero and the binder will move at its terminal velocity (steady speed)
What does a parachute do to reduce the parachutists terminal velocity
A parachute had a large surface area and they will fall more slowly because they experience more air resistance
When is the line on a velocity time graph horizontal
When an object is moving with constant velocity
What does the line on a velocity time graph look like when an object is moving with a steadily increasing or decreasing velocity
Straight but sloped
The more rapidly the velocity of the object is changing,
The steeper the line
What’s the relationship between weight mass and gravitational field strength
Weight = mass x gravitational field strength
What may a force acting on an object cause
A change in the shape of the object
What means that an object behaves elastically
If it returns to its original shape when the force is removed
What will a force being applied on an elastic object such as a string result in
The object will stretch and store elastic potential energy
For an object behaving elastically, the extension is directly proportional to what
The extension is directly proportional to the force applied, provided that he limit of proportionality is not exceeded F = k x e
When is work done
When a force causes an object to move through a distance
What is the relationship between work done, force and distance moved in the direction of the force
Work done = force x distance moved in the direction of the force
When is energy transferred
When work is done
What does work done against frictional forces cause
Energy transfer by beating
What happens when brakes are applied in disc brakes
When the brakes are applied, the pads are pushed onto the disc in each wheel Friction between the pads and each disc slows the wheel down Some of the kinetic energy of the car is transferred to energy heating the disc pads and the disc
What is the relationship between power, work Done or energy transferred and time
Power = energy transferred / time
What is the relationship between gravitational potential energy, mass, gravitational field strength (acceleration of free fall and height
Gravitational potential energy = mass x gravitational field strength x height
What is the relationship between kinetic energy, mass and speed
Kinetic energy = 1/2 x mass x speed squared
An object of double he mass of another object travelling with the same speed will have …
Double the kinetic energy
An object travelling at double the speed of another object with the same mass will have…
Four times the kinetic energy
What is the relationship between time period and frequency
Time period = 1 / frequency
The time period of a pendulum depends on
It’s length
What are examples of applications of the pendulum
Simple fairground and playground rides
When an object moves in a circle it
Continually accelerates towards the centre of the circle The resultant force causing this acceleration is called the centripetal force
Where is the centripetal force always directed
Towards the centre of the circle
The centripetal force needed to make an object perform circular motion increases as
The mass of the object increases The speed of the object increases The radius of the circle decreases
Velocity, displacement , time taken letter equation
v = s / t
Acceleration velocity and time taken letter equation
a = ( v - u ) / t
Does momentum have direction
Yes
Momentum, mass and velocity letter equation
p = m x v
