Question

A rocket weighs 1 x10^7 N while on the surface of the earth.

Theignition of its engines results in a lift off force of 1.5 X
10^7N

a) what is the mass of the rocket.
b) what is its acceleration at lift -off
c)How fast will it be moving if it acceleartion at this rates for10
minutes.
d) How high will it be after 10 minutes.

Answer 1

(a)
`1.02* 10^(6)\ kg`

(b) a =
`4.9\ m/s^(2)`

(c) v' = 2940 m/s

(d) h = 1764 km

Solution:

As per the question:

Weight of the rocket, W =
`1* 10^(7)\ N`

Lift-off force, F =
`1.5* 10^(7)\ N`

Now,

To calculate:

(a) Mass of the rocket:

Calculate the mass from the weight of the rocket:

W = mg

where

m = mass of the rocket

Thus

`m = (W)/(g) = (1* 10^(7))/(9.8) = []</p><p>(b) To calculate acceleration at lift-off:</p><p>F = m(g + a)</p><p>[tex]a + g = (1.5* 10^(7))/(1.02* 10^(6))`

a = 14.7 - g = 14.7 - 9.8 =
`4.9\ m/s^(2)`

(c) To calculate the velocity:

Use kinematic eqn:

v' = u + at

u = initial velocity = 0 m/s

v' = at =
`4.9* 10* 60 = 2940 m/s`

(d) To calculate the height, h:

Use kinematic eqn:

`h = (1)/(2)gt^(2) = 0.5* 9.8* (10* 60)^(2) = 1764000\ m = 1764\ km`