We know, by conservation of energy :

Therefore,

Putting given values, we get :

Therefore, the spring be compressed to 6.93 cm to send the ball twice as high.
Hence, this is the required solution.
Both don’t have units beacuse they are ratios
Answer:
The recoil velocity is 0.354 m/s.
Explanation:
Given that,
Mass of hunter = 70 kg
Mass of bullet = 42 g = 0.042 kg
Speed of bullet = 590 m/s
We need to calculate the recoil speed of hunter
Using conservation of momentum

Where,
= mass of hunter
= mass of bullet
u = initial velocity
v = recoil velocity
Put the value in the equation



Hence, The recoil velocity is 0.354 m/s.
Answer:
charcoal is the correct answer
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