Acceleration = (Vf - Vi)/t
Since Vf= 60m/s
Vi= 15m/s
T= 15s
=> a= (60m/s - 15m/s)/15s
= 3
So the acceleration is 3m/s^2
To solve this problem it is necessary to apply the kinematic equations of motion.
By definition we know that the position of a body is given by

Where
Initial position
Initial velocity
a = Acceleration
t= time
And the velocity can be expressed as,

Where,

For our case we have that there is neither initial position nor initial velocity, then

With our values we have
, rearranging to find a,



Therefore the final velocity would be



Therefore the final velocity is 81.14m/s
Answer:
the quantity of matter contained in a body is called mass .si unit of mass is kilogram.weight is effected by gravity but mass is not effected by gravity.
The energy of a photon is given by

where

is the Planck constant
f is the frequency of the photon
In our problem, the frequency of the light is

therefore we can use the previous equation to calculate the energy of each photon of the green light emitted by the lamp: