Question

A train with mass 3.3 x 107 kg starts from rest and accelerates to a speed of 42

m/s. What is the initial kinetic energy of the train?

Answer 1

Answer: The initial kinetic energy of the train is
`2910.6 * 10^(7) J`.

Step-by-step explanation:

Given: Mass =
`3.3 * 10^(7) kg`

Speed = 42 m/s

Kinetic energy is the energy acquired by an object due to its motion.

Formula to calculate kinetic energy is as follows.

`K.E = (1)/(2)mv^(2)`

where,

m = mass of object

v = speed of object

Substitute the values into above formula as follows.

`K.E = (1)/(2)mv^(2)\\= (1)/(2) * 3.3 * 10^(7) kg * (42 m/s)^(2)\\= 2910.6 * 10^(7) kg m^(2)/s^(2) (1 J = 1 kg m^(2)/s^(2))\\= 2910.6 * 10^(7) J`

Thus, we can conclude that the initial kinetic energy of the train is
`2910.6 * 10^(7) J`.

Answer 2

kinetic energy of the train = 2,910.6 x 10⁷ joule

Step-by-step explanation:

Given:

Mass of train = 3.3 x 10⁷ kg

Speed of train = 42 m/s

Find:

kinetic energy of the train

Computation:

kinetic energy = (1/2)(m)(v²)

kinetic energy of the train = (1/2)(3.3 x 10⁷)(42²)

kinetic energy of the train = (1/2)(3.3 x 10⁷)(1,764)

kinetic energy of the train = (3.3 x 10⁷)(882)

kinetic energy of the train = 2,910.6 x 10⁷ joule