Answer:
a=positive
b=0
c=positive
d=negative
Explanation:
a=acceleration depends on the speed and time. if the speed and time are increasing at the same rate, the acceleration value will be positive as the vehicle is speeding up.
b=the speed and time are not increasing, therefore the vehicle is either stationary or travelling at a steady pace.
c=same explanation as a
d=the speed and time are not increasing at the same rate as the speed is decreasing. this means that the car is slowing down
It's called a star when it creates its own energy
The bigger one as the luminosity has a direct exponential relationship with R of the star so the star which has more surface area will be more luminous than the smaller one
