Our Dynamic Universe Flashcards
Acceleration definition
The rate of change of velocity
What is the gradient of a displacement-time graph
Velocity
What does the gradient of a velocity-time graph equal
Acceleration
What happens to a velocity time graph when an object changes direction
The graph crosses the X axis
How would you find the displacement from a velocity-time graph
The area underneath the graph
What is the definition of a satellite
They are in free fall around a planet or star. They are constantly accelerating but not changing speed- this is because the direction, not the magnitude, of their velocity is changing. The surface of the planet or star curves away from the satellite at the same rate that the satellite curves towards it hence the satellite remains in orbit at a constant altitude.
How to calculate the horizontal of projectiles of the component of velocity
U=Ucos(angle)
Projectiles
Component of velocity vertically
U=Usin(angle)
In projectiles calculate the horizontal distance
d=vt
Speed distance time
Newton’s first law
An object will stay at rest or move with a constant speed unless acted upon by an unbalanced force
Balanced forces
Have the same size of force acting in opposite directions on an object.
Constant velocity=balanced forces
Newton’s second law
F=ma
Unbalanced force equals mass times acceleration.
Newton’s third law
For every action (force) there is an equal and opposite reaction (force).
Friction
Friction is a force which always acts in the opposite direction to an object’s motion.
Tension
Tension is a force that acts both ways at the same the time.
The definition of air resistance
It increases with speed
The effect that a lift has on wieght
Scales measure the upwards force on the person and that the weight (acting downwards) is constant.
How to calculate the component of weight acting down a slope
Slope=mg sin (angle)
The law of conservation of linear momentum
The total momentum before is equal to the total momentum after a collision in the absence of external forces
Remember that when working with momentum before and after objects going different direction, one will be a negative velocity
Elastic collision
Kinetic energy is conserved
Inelastic collision
Kinetic energy is not conserved
Definition of impulse
Change in momentum
Area under a force-time graph
Remember that when using Newtons universal law of Gravitation to measure the distance from the centre of the first mass to the centre of the second mass!
The speed of light in a vacuum is the same for all observers
