Topic 2 - Motion and Forces Flashcards
What is the difference between a scalar and vector quantity?
Scalar quantities only have magnitude
Vector quantities have both magnitude and direction
Define a resultant force
The net force acting on an object after all opposing forces are balanced out.
State Newton’s 1st law
An object will remain at a constant velocity unless acted upon by a resultant force
Define mass
A scalar measurement of the amount of substance there is in an object (kg)
Define weight
A force due to the pull of gravity on an object (N)
Vector quantity
State the equation for weight
weight = mass * gravity
Weight (N)
Mass (kg)
Gravity (N/kg)
State Newton’s second law
Acceleration in the direction of a resultant force depends on:
1. Magnitude of force
2. Mass of object
Force = mass * acceleration
State Newton’s 3rd law
For every action there is an equal and opposite reaction
What are action reaction forces?
Are a pair of forces on interacting objects, of the same size and in opposite directions always acting on different objects.
How do you measure human reaction time?
- Have them hold a ruler while you have your hand at 0cm
- The person should drop the ruler without teeling you when and record at which length you caught the ruler.
- Then use the formula v squared - u squared = 2as to calculate the velocity
- Then use a = (v-u) / t in order to calculate the time
How to calculate stopping distance
Thinking distance + braking distance
State variables that impact the stopping distance of a vehicle
- Mass of vehicle
- Driver’s reaction time
- Conditions of road
- Speed of vehicle
- Conditions of vehicle’s brakes
- Friction between road and tire
State the variables that could impact a driver’s reaction time
- Ditractions
- Alcohol
- Drugs
- Tiredness
What happens to braking distance when speed doubles
Braking distance quadruples (*4)
