Forces And Motion: Forces And Motion Flashcards
What is the equation for Newtons 2nd Law?
Force = Mass*Acceleration or F = m*a
What is the relationship (equation) between weight, mass and g?
Weight = mass*g
What is the gravitational field strength measured in?
N/kg
When would your weight change?
Weight = mass*g and since mass is constant, g would have to change for your weight to change. G is 1.7 on the moon so if you went to the moon your weight would change.
What main forces will act on you if you fall through a fluid.
Gravitational force (downwards) and frictional force (upwards), ignoring Archimedean force.
How is the size of the resistive force relative to the speed on a falling object?
The size the resistive force is approximately on the speed squared. The resistive force is the drag force.
What will initially happen as a skydiver jumps out of a plane?
There will be zero resistive force and she will be accelerating downwards a rate of 10m/s/s.
What will happen when a skydiver picks up speed?
The drag force grows, reducing the overall force downwards and thus reducing the acceleration.
What will eventually happen to a free falling skydiver?
The resistive force will become equal to the weight making the overall force and acceleration zero so the object will now fall at a constant velocity.
What is it called when an object is falling at a constant velocity?
Terminal velocity.
What happens when a skydiver at terminal velocity opens their parachute?
The resistive force is larger than the weight of the skydiver so he is decelerating (but still falling downwards) until his speed falls to a point where his weight again balances the drag force. He will reach terminal velocity again.
What is the overall stopping distance?
A sum of the thinking and breaking distance.
What is the thinking distance?
The distance you travel while thinking about putting your foot on the break.
What is the breaking distance?
The distance the car travels once the breaks have been applied.
How is the thinking distance related to the speed you are driving at?
It is proportional to the speed.
