Questions Corrections Flashcards
Three factors that increase the braking distance
Wet/icy roads
Poor conditions of brakes
Explain why the drivers reaction time affects the thinking distance of a car
Distance=speed x time
So the longer the reaction time the greater the distance
The average speed of a car between the cameras and average velocity of the car between cameras are different
Velocity is a vector quantity and speed is scalar
The road is not straight
Therefore direction changes so velocity changes
Why does a hailstone accelerate
There is a resultant force acting
Explain why the hailstone reaches terminal velocity
As the velocity of the hailstone increases the air resistance increases
Until air resistance becomes equal to the weight of the hailstone
So the resultant force is zero
Explain the difference in the maximum kinetic energy of a hailstone with a mass of 10g and a hailstone with a mass of 20g
Kinetic energy depends on both mass and velocity
As mass increases so does terminal velocity
Kinetic energy is directly proportional to mass and velocity squared so as the mass doubles kinetic energy more than doubles
What is the centre of mass
The point from which weights may be considered to act
What is one property of the spring that makes it suitable for use in the mass balance
Deforms elastically
So will return to original shape after force is removed
What is red shift
The observed increase in wavelength
As galaxies move away from us
Explain why there is an alternating current in the output where the transformer is connected to a circuit
The AC causes a changing magnetic field around the primary coil
Creates magnetic field that changes direction in the core
This induces an alternating potential difference across the secondary coil
Explain why the forces on the brick at the bottom of the pool cause it to be stationary
Upthrust acts upward on the brick
Normal contact force acts upwards on the brick
Weight is equal to upthrust plus normal contact force (so resultant force is zero)
