Answer:
There is an interval of 24.28s in which the rocket is above the ground.
Explanation:





From Kinematics, the position
as a function of time when the engine still works will be:

At what time the altitud will be
?
⇒ 
Using the quadratic formula:
.
How much time does it take for the rocket to touch the ground? No the function of position is:

Where our new initial position is
, the velocity when the engine breaks is
and the only acceleration comes from gravity (which points down).
Now, when the rocket tounches the ground:
Again, using the quadratic ecuation:

Now, the total time from the moment it takes off and the moment it tounches the ground will be:
.
Answer:
The average power provided by the tension in the cable pulling the lift is = 714 W
Explanation:
Given data
Mass = 71 kg
Change in height = 123 m
When the lift moves in upward direction then in that case kinetic energy is constant & only potential energy changes.
Change in potential energy Δ PE = m g (
)
Δ PE = 71 × 9.81 × 123
Δ PE = 85670.73 J
Time = 2 min = 120 sec
So average power is given by



Therefore the average power provided by the tension in the cable pulling the lift is = 714 W
Answer:
no energy is lost or gained when molecules collide
molecules are constant, linear motion
Explanation:
Answer: 5184 kJ
Explanation:
Given
Area of cross-section 
thickness of slab 
thermal conductivity 
temperature difference 
Heat flow is given by

for 2 days time period, it is

Heat flow in 2 days

<span>the degree of compactness of a substance.</span>