The answer is electricity
Answer:

Explanation:
Given that
Mass of rifle = M
Initial velocity ,u= 0
Mass of bullet = m
velocity of bullet = v
Lets take final speed of the rifle is V
There is no any external force ,that is why linear momentum of the system will be conserve.
Initial linear momentum = Final linear momentum
M x 0 + m x 0 = M x V + m v
0 = M x V + m v

Negative sign indicates that ,the recoil velocity will be opposite to the direction of bullet velocity.
Answer:
0.5A
Explanation:
Using
,
R is the resistance (in Ohms)
V is the voltage (in V)
I is the current (in A)

I = 0.5A
Answer:
a baseball flying through the air at 90 miles per hour
Explanation:
For the question, Therefore, the kinetic energy of an object is proportional to the square of its velocity (speed). In other words, If the velocity is doubled the kinetic energy will increase by a factor of four.