Could someone clarify the answers to these physics problems? (1 Viewer)

[sciencenerd]

(b, c and d confuse me )

i)The instruments attached to a weather balloon have a mass of 5kg. The balloon is released and exerts an upward force of 98N on the instruments.

a) what is the acceleration of the instruments?

b)after the balloon has accelerated for ten seconds the attachment to the instruments breaks. what is the velocity of the instruments at the moment it breaks?

c)what net force acts on the instruments after the break?

d)at what time does the instrument package start heading towards the ground?

AND

ii) describe how you would apply the law of conservation of momentum to slow a spaceship that is moving at high speed.


THANK YOU!

 

[anomalousdecay]

(b, c and d confuse me )

i)The instruments attached to a weather balloon have a mass of 5kg. The balloon is released and exerts an upward force of 98N on the instruments.

a) what is the acceleration of the instruments?

b)after the balloon has accelerated for ten seconds the attachment to the instruments breaks. what is the velocity of the instruments at the moment it breaks?

c)what net force acts on the instruments after the break?

d)at what time does the instrument package start heading towards the ground?

AND

ii) describe how you would apply the law of conservation of momentum to slow a spaceship that is moving at high speed.


THANK YOU!

First one is 9.8 m/s^2 upwards. Do you understand how to get this using the sum of external forces?

Total net force will be 49N up and hence it accelerates at 9.8 m s^-2 up.

b) Use the formula:



The initial velocity is zero, it accelerates upwards for 10 seconds at 9.8 m s^-2

So:



c) Net force is that due to gravitational force as it is the only force acting on them after the string breaks. So 49N downwards towards earth. (or minus 49N).

d) So here, we have:






Using:



We get t = 10 seconds



ii) So momentum is conserved in an elastic system. Assuming an elastic system, by exerting gases out of the rocket in the direction it is travelling, by conservation of momentum you can slow it down as the momentum of the gases plus the momentum of the rocket must be equal to the original momentum of the rocket before the gases were exerted.