Question
Question: A stream of water strikes a stationary turbine blade as shown. The speed of water v is 3m/s both bef...
A stream of water strikes a stationary turbine blade as shown. The speed of water v is 3m/s both before and after it strikes the curved surface of the blade and the constant rate at which the mass of water strikes is 5 kg/second. The magnitude of the force on the blade from the water is:
A
30 N
B
15 N
C
7.5 N
D
5 N
Answer
30 N
Explanation
Solution
After the release, both blocks move together till spring acquires natural length. Afterwards m2 moves with constant speed (Aω) and m1 slows down as direction of spring force is reversed. Spring is fully stretched when m1 stops. Time taken by m1 from mean position to the end is T/4.
F = dp/dt = 2v dm/dt = 30 N.