A model rocket has a mass of 0.12 kg.

Question

 It accelerates vertically from rest to 60.0 m/s in 1.2 s.? 

 

 

(a) What is the average acceleration? 
(b) What is the net force on the rocket? (Ignore air resistance.) 
(c) If the force of gravity on the rocket is 1.20 N, what is the total thrust of the engine?

 

 

Answer 1

(a)

Mass of model rocket is 0.12 kg .

Velocity of the rocket is 60 m/s at 1.2 sec .

Acceleration = ( change in velocity ) / ( change in time ) 

Rocket start from rest so the velocity when the rocket is at rest is 0 .

Acceleration = (final velocity - initial velocity) / (time duration)

Acceleration = (60 m/s - 0) / ( 1.2 s) 

Acceleration a = 60 m/s / 1.2s

Acceleration a = 50 m/s² 

So the average acceleration a is  50 m/s² .

Answer 2

(b)

Mass of model rocket is 0.12 kg .

Velocity of the rocket is 60 m/s at 1.2 sec .

The net force on the rocket can be evaluted using the newton's second law .

                                                                F = ma 

So first evalute for the acceleration of the rocket .

Acceleration = ( change in velocity ) / ( change in time ) 

Rocket start from rest so the velocity when the rocket is at rest is 0 .

Acceleration = (final velocity - initial velocity) / (time duration)

Acceleration = (60 m/s - 0) / ( 1.2 s) 

Acceleration a = 60 m/s / 1.2s

Acceleration a = 50 m/s² 

Net force F = ma 

              F = (0.12)(50)

              F = 6

So the net force is 6 N . 

Answer 3

(c)

Mass of model rocket is 0.12 kg .

Velocity of the rocket is 60 m/s at 1.2 sec .

 Force due to gravity is 1.2 N .

Net force = ma = Thrust – Force due to gravity .

The net force on the rocket can be evaluated using the newton's second law .

                                                                F = ma 

So first evaluate for the acceleration of the rocket .

Acceleration = ( change in velocity ) / ( change in time ) 

Rocket start from rest so the velocity when the rocket is at rest is 0 .

Acceleration = (final velocity - initial velocity) / (time duration)

Acceleration = (60 m/s - 0) / ( 1.2 s) 

Acceleration a = 60 m/s / 1.2s

Acceleration a = 50 m/s² 

Net force F = ma 

              F = (0.12)(50)

              F = 6 N

Net force =  Thrust – Force due to gravity .

Thrust = Net force +  Force due to gravity .

Thrust = 6 + 1.2 

Thrust = 7.2 N

So total thrust of engine is 7.2 N .