P10 Force and Motion P14 Light Flashcards
Resultant Force Equation:
Mass x acceleration
Newton’s second law of motion
States that acceleration of an object is proportional to the resultant force of the object
States that acceleration of an object is inversely proportional to the mass of the object
What is the inertia of an object
It’s tendency to stay at rest or in uniform motion
What’s the weight of an object
The force acting on the object due to gravity. It’s mass is the quantity of matter in the object
At what speed of an object active only by gravity accelerate at
10 mph squared
Terminal velocity
The terminal velocity of an object is the velocity it eventually reaches when it is falling. The weight of the object is that equal to the frictional force on the object
What is the resultant force on an object moving at its terminal velocity
Zero
What does the stopping distance depend on
The braking distance and the thinking distance
What is opposes the driving force of the vehicle
Friction and air resistance
Thinking distance
The distance travelled by the vehicle in the time it takes the driver to react (reaction time)
Stopping distance
This is the shortest distance of the vehicle can safely stop in
Breaking distance
The distance travelled by the vehicle during the time the braking force acts
Equation for stopping distance
Thinking distance + braking distance
What sort of factors increase braking distance
High-speed, poor weather conditions and poor vehicle maintenance
What sort of factors increase thinking distance
Poor reaction time due to tiredness alcohol drugs or using a mobile phone and high-speed both increase the thinking distance
Equation for breaking force of the vehicle
F= m x a
Equation for momentum
p = m x v
Momentum units
kg m/s
Momentum is an example of what
A vector quantity
What is a close system in the context of momentum
A system in which the total momentum before an event is the same as the total amount momentum after the event. This is called conservation of momentum
What happens when two objects push each other apart
They move a different speeds if they have unequal masses and with equal and opposite momentum so the total momentum is zero
Equation for momentum, when two objects recoil from each other
m1 v1 + m2 v2 = 0