Answer
i'm not 100% sure but 1764
Explanation:
Work done = gravitational potential energy
Gravitational potential energy = mass(kg) × height(m) × gravitational field strength(N/kg)
We can assume that the student is on earth so the gravitational field strength is 9.8N/kg
So work done = 60 × 3×9.8
=1764
(if you need help calculating power but if you do just divide your answer by 12 and you will get 147)
Given that,
Mass of trackler, m₁ = 100 kg
Speed of trackler, u₁ = 2.6 m/s
Mass of halfback, m₂ = 92 kg
Speed of halfback, u₂ = -5 m/s (direction is opposite)
To find,
Mutual speed immediately after the collision.
Solution,
The momentum of the system remains conserved in this case. Let v is the mutual speed after the collision. Using conservation of momentum as :

So, the mutual speed immediately after the collision is 1.04 m/s but in opposite direction.
You would use distance an time formula to mathmaticly solve
Answer:
The conditions necessary for hearing the echo. The distance between the sound source and the reflecting surface must not be less than 17 metres where the time period between hearing the original sound and its echo should not be less than 0.1 of a second.