Topic 5- Force And Motion Flashcards
Why can an object travelling at constant speed in a circle not have constant velocity?
Velocity is vector- can only be constant if direction is constant
Circular motion- direction is continuously changing
How can speed be calculated from a distance- time graph
Speed= gradient of the graph
How can you calculate distance travelled by an object on a velocity time graph
Distance travelled is equal to the area under the line
What can be said about the resultant force acting on an object when falling at terminal velocity
Resultant force is zero
At terminal velocity, object is moving at constant speed so isn’t accelerating
What is newtons first law for a stationary object
If resultant force on stationary object= zero, object will remain at rest
What is Newton’s first law for a moving object
If resultant force on moving object- zero, object will remain at constant velocity
If object changes direction, but remains at constant speed, is there a change in resultant force?
Velocity will change as direction has been changed, so there must be a resultant force
What is inertia?
Tendency of an object to continue in its state of rest or uniform motion
What is Newton’s second law?
Object’s acceleration is directly proportional to resultant force acting on it and inversely proportional to its mass
State Newton’s third law
Whenever 2 objects interact, forces they exert on each other are always equal and opposite
What is a vehicle’s stopping distance equal to?
Thinking distance + braking distance
Give 3 factors that can affect a drivers reaction time
Tiredness
Alcohol
Age
Give 2 factors that could affect braking distance
Wet/icy road conditions
Poor tyre conditions
What are the energy transfers when a car applies brakes?
Work done by friction force between brakes and wheel
Wheel’s kinetic energy is converted to heat and dispersed to surroundings
What is intertial mass?
Measure of how difficult it is to change a given object’s velocity
Ratio of force over acceleration
