1. derive an expression for the energy needed to launch an object from the surface of earth to a height h above the surface.
express your answer in terms of some or all of the variables h, mass of the object m, mass of earth me, its radius re, and gravitational constant g.

2. ignoring earth's rotation, how much energy is needed to get the same object into orbit at height h?
express your answer in terms of some or all of the variables h, mass of the object m, mass of earth me, its radius re, and gravitational constant g.

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

gravitational energy

electrical energy

kinetic energy

ligh energy