topic 5 Flashcards
what is force
a vector quantity
what do vector quantities have
A magnitude or direction
4 examples of vector quantities
- Force
- Acceleration
- Momentum
- displacement
what are scalar quantities
physical quantities that have magnitude but no direction
5 examples of scalar quantities
- Speed
- Mass
- Time
- Temp
- Distance
what does the length of the vector quantity show
its magnitude
what does the arrow in vector quantities show
the direction of the quantity
what quantity is speed
scalar
what are all forces
contact or non-contact forces
what is a contact force
when two objects have to be touching for a force to act
what is a non-contact force
if the objects do not need touching for the force to act
what is an interaction pair
a pair of forces that are equal and opposite and act on two interacting objects
(Momentum) the greater the mass of an object or the greater its velocity …
The momentum the object has
What quantity is momentum
A vector quantity- it has size and direction
Momentum (kg m/s) =
Mass (kg) X velocity (m/s)
What is “conservation of momentum”
In a closed system the total momentum before an event is the same as after the event
Stopping distance =
Thinking distance + braking distance
What is your thinking distance affected by?
- speed
- your reaction time
What is braking distance affected by?
- speed
- weather
- condition of tyres
- how good the brakes are
What is the breaking distance of 30mph?
14 m
What is the braking distance of 60 mph?
55 m
What is the braking distance of 70mph?
75 m
The work done between the brakes and the wheels transfers energy from the …
Kinetic energy stores of the wheels to the thermal energy stores of the brakes
What does a larger braking force mean
A larger deceleration
The faster a vehicle is going …
The more energy it has in its kinetic stores, so the more work needs to be done to stop it
What is inertia
The tendency to continue in the same state of motion
What does an objects inertial mass measure
How difficult it is to change the velocity of an object
What is Newtons third law
When 2 objects interact, the forces they exert in each other are equal and opposite
What does newtons first law state
That a resultant force is needed to make something start moving, speed up or slow down
What will a non-zero resultant force always produce
Acceleration or deceleration in the direction of the force
The larger the resultant force acting on an object ..
The more the object accelerates
Force and acceleration are ..
Directly proportional
What is acceleration inversely proportional to
The mass of the object
What 5 forms can acceleration take
- stopping
- speeding up
- slowing down
- changing direction
- starting
What is drag
The resistance you get in a fluid (a gas or a liquid(
Give an example of a type of drag
Air resistance
What is the important factor in reducing drag
Keeping the shape of the object streamlined
