Answer:

Explanation:
Given:
- mass of rocket,

- time of observation,

- mass lost by the rocket by expulsion of air,

- velocity of air,

<u>Now the momentum of air will be equal to the momentum of rocket in the opposite direction: </u>(Using the theory of elastic collision)



Answer:
The work done by friction was 
Explanation:
Given that,
Mass of car = 1000 kg
Initial speed of car =108 km/h =30 m/s
When the car is stop by brakes.
Then, final speed of car will be zero.
We need to calculate the work done by friction
Using formula of work done



Put the value of m and v



Hence, The work done by friction was 
Answer:
Explanation:
Spring has a tendency to store energy in them and deform its shape when force is applied on it. Once the applied force is removed it regains its original shape and size.
It is in helical shape and is used in mattress to give structure and support. Spring have elastic nature and follows spring forces, F = k * x
where is the applied force, k is the spring constant and x is the amount of extension.
When a heavier person sits on a mattress, more weight is applied on springs and they form coils, as weight is removed they regains its shape again.
i think it’s B. sorry if i’m wrong
Answer: como mi llamo yo?
Explanation: in rlf Maria