Question

Question 5.9 A rocket with a lift-off mass 20,000 kg is blasted upwards with an initial acceleration of 5.0 m s–2. Calculate the initial thrust (force) of the blast.

Chapter Laws Of Motion Page 110

Answer 1

ANSWER
>>>>>>>>>>>>>>>>>>>>>>>>
INITIAL FORCE = MASS × INITIAL ACCELERATION

Force = Mass × Acceleration
Force = 20000 kg × 5 m/sec ^2

Force = 1,00,000 N

>>>>>>>>>>>>>>>>>>>>≥≥>>>>>>>
ANSWER = 100000 N
>>>>>>>>>>>>>>>>>>>>>>

Answer 2

Mass of rocket = 20000 Kg
Initial acceleration = 5m/s² { upward direction }

Let initial thurst of the blast = T
using Newton second law,
Fnet = upward force - downward force
ma = T - mg
T = mg+ ma
= m( g + a)
= m(10 + 5) { g = 10m/s²}
= 15m = 15 × 20000 N
= 300000 = 3 × 10^5 N