The diagram shows a ball of 0.4 kg mass being released from a height of 5 m above the ground. A is the initial position of the ball. B is the position of the ball at the moment before it hits the ground. 1)what is the gravitational potential energy of the ball at position A?
[gravitational field strength, g = 10 N m s-2]

2)the ball achieves a maximum speed of 10 m s-1 at position B. what is the kinetic energy of the ball at position B?

3)compare the amount of energy obtained in question 1&2. give an explanation for the result.

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s

answerdmitry mendeleyev made a workable classification of the elements