-
What is a scalar quantity?
Only has a size
-
What is a vector quantity?
Has a size and a direction
-
What is a relative speed?
How fast something is going relative to something else
-
What are four equations of motion?
- s = (u + v)/2 xt
- v = u + at
- s = ut + 0.5at2v2 = u2 + 2as
-
What does 'u' represent?
Initial velocity
-
What does 'v' represent?
Final velocity
-
What does 's' represent?
Displacement (distance)
-
What does 't' represent?
Time
-
What does 'a' represent?
Acceleration
-
What is a projectile?
Something that is projected, or dropped, and from then on only has Earth's gravitational field strength acting on it (ignoring air resistance)
-
What shape is the path of a projectile?
Parabolic
-
What is the overall/resultant velocity of the ball?
The vector sum of the horizontal and vertical motion
-
What do projectile calculations use?
The equations of motion
-
When do forces occur?
When two objects interact
-
What are the two forces sometimes called?
An interaction pair
-
What are two examples of acting forces?
-
How does recoil involve forces?
- When a gun is fired, the bullet exerts a force on the gun equal and opposite to the force exerted by the gun on the bullet
- So, the bullet travels out of the barrel and the gun recoils in the opposite direction
- The bullet travels much faster forwards than the gun does backwards because the bullet is much lighter
-
How do rockets use forces?
- When gas particles collide with things they exert a force on them
- In a rocket engine particles of hot gas collide with the walls, exerting a force on the walls and the wall exerts an equal force on them
- The force from the wall pushes the gas particles out of the exhaust
- The force from the gas on the wall pushes the rocket forwards
- The force pushing the rocket upwards must be larger than the force of gravity and air resistance of it won't take off
- So, for large rockets, used to lift satellites into orbit above Earth, you need a large number of particles moving at high speed to produce enough force to lift the rocket
-
How can you work out momentum?
momentum = mass x velocity
-
What is momentum before equal to?
- Momentum after
- Momentum is conserved
-
What does 'm1' represent?
Mass of the first object
-
What does 'm2' represent?
Mass of second object
-
What does 'u1' represent?
Velocity of first object
-
What does 'u2' represent?
Velocity of second object
-
What does 'v' represent?
Velocity of combined objects
-
What does kinetic energy say about gases?
They are randomly moving particles
|
|