Forces P2 Flashcards
What does a horizontal line, gradient and curves show on distance time graphs
Horizontal line shows stationary and straight non horizontal lines show constant speed
Gradient is the speed (the steeper the slope the greater the speed)
Curves show either acceleration or deceleration depending on gradient
What is the difference between a vector and scalar quantity
Vector has magnitude and direction (forces and velocity)
Scalar only has magnitude (speed and temperature)
What do horizontal lines and straight non horizontal lines represent on a velocity time graph
Horizontal lines show constant speed
Straight non horizontal lines show acceleration or deceleration
How do you work out the distance traveled on a velocity time graph
Work out the area under the graph
Two cars head towards eachother with speeds of 20m/s and 30m/s what’s their relative velocity
It is 50m/s as the cars will seem faster when going past eachother
What’s the acceleration formula
Acceleration = change in speed / time
How do you work out average speed
Average speed = total distance / total time
What are the different types of force and what do they do
Electrostatic (repulsion or attraction due to charge)
Gravity (all masses attract eachother)
Magnetism (repulsion or attraction)
Normal force (repulsive force when objects touch)
Friction (when 2 surfaces move past eachother)
What’s Newtons first law
If the force acting are balanced the resultant force will always be zero and there is no change to the object
What’s Newtons second law
If the forces acting on a body are unbalanced the resultant force will never be zero and the objective will change
What’s Newtons third law
For every action there is an equal opposite reaction
What is inertia
Inertia is the resistance of any object to any change in its velocity (the tendency of objects to keep moving in a straight line at constant velocity)
Explain what happens when a person jumps out a plane
1) Weight first act as a force and is unbalanced so you accelerate
2) As the speed increases so does drag the forces are unbalanced but there is a less resultant force so less acceleration
3) the forces become balanced meaning they are now at a constant speed (TERMINAL VELOCITY)
4) the parachute opens making drag bigger causing you to decelerate as forces are unbalanced
5) eventually the drag will be equal to weight again making forces balanced so you are at terminal velocity
6) you then land and weight is equal to normal constant force meaning you are stationary
What is momentum
Momentum is a vector scale
It is defined as the mass of an object multiplied by it’s velocity (if an object is stationary the momentum is 0)
Objects moving right have a positive velocity. Objects moving left have negative velocity.
MOMENTUM=MASS X VELOCITY
Explain circular motion
Speed is constant
The direction is changing and so is velocity as it’s speed and direction
