Given that,
Mass of the stone, m = 400 g = 0.4 kg
Initial speed, u = 20 m/s
It is climbed to a height of 12 m.
To find,
The work done by the resistance force.
Solution,
Let v is the final speed. It can be calculated by using the conservation of energy.

Work done is equal to the change in kinetic energy. It can be given as follows :

So, the required work done is 32.99 J.
Answer:
681.6/ms
Explanation:
A reconnaissance plane flies 545 km away from its base at 568 m/s. then flies back to its base at 852 m/s.
What is its average speed?
Answer in its of m/s
Avg speed of the round trip is
2*568*852/(568+852)= 681.6/ms
The formula for this problem that we will be using is:
F * cos α = m * g * μs where:F = 800m = 87g = 9.8
cos α = m*g*μs/F= 87*9.8*0.55/800= 0.59 So solving the alpha, find the arccos above.
α = arccos 0.59 = 54 ° is the largest value of alpha
210J
PE is mgh in this context.