Answer:
The velocity is 
Explanation:
From the question we are told that
The first distance is 
The first speed is 
The second distance is 
The second speed is 
Generally the time taken for first distance is



The time taken for second distance is



The total time is mathematically represented as

=> 
=> 
Generally the constant velocity that would let her finish at the same time is mathematically represented as

=> 
=> 
Answer:
Explanation:
mass of first marble 
Initial velocity of the first marble
considering right side as positive
Mass of second marble
After collision first marble moves to the left with a velocity of 18 cm/s
i.e. 
considering
be the velocity of second marble after collision
The Coefficient of restitution is 1 for an elastic collision

Putting values

So, the velocity of the second marble is 22.5 m/s to the right after the collision
(b)Initial kinetic energy =
Final kinetic energy=

Period = (1) / (frequency)
= (1) / (20/sec)
= 1/20 sec
<span>The student's power rating is approximately 800W.
</span>
Power is the rate of doing work. Its SI unit is Watt. 1 W = 1J/sec
Given: <span>The work done to get to the top is 1200 Joules
</span>
Time = 1.5 seconds.
Power =