The work done to pull the sled up to the hill is given by

where
F is the intensity of the force
d is the distance where the force is applied.
In our problem, the work done is

and the distance through which the force is applied is

, so we can calculate the average force by re-arranging the previous equation and by using these data:
Answer:
The equation v – = v 0 + v 2 v – = v 0 + v 2 is reflects the fact that when acceleration is constant, v – is just the simple average of the initial and final velocities.
Explanation:
hope this is it
Can you please translate to English?
Question
What is the length of the pipe?
Answer:
(a) 0.52m
(b) f2=640 Hz and f3=960 Hz
(c) 352.9 Hz
Explanation:
For an open pipe, the velocity is given by

Making L the subject then

Where f is the frequency, L is the length, n is harmonic number, v is velocity
Substituting 1 for n, 320 Hz for f and 331 m/s for v then

(b)
The next two harmonics is given by
f2=2fi
f3=3fi
f2=3*320=640 Hz
f3=3*320=960 Hz
Alternatively,
and 

(c)
When v=367 m/s then

Answer:(a) 2.40 (b) horizontal distance. (c) 0.630. (d) 6.50
Explanation:that's all is talking about a speed and distance and time right