(a) You must have seen the definition of kinetic energy, which is
(1/2) M V^2
You have been told the mass M and the velocity V. Just do the calculation. The mass will have to be in kg if you want the answer in joules.
(b) Final kinetic energy = (average force)*(distance over which the force is applied)
(1/2)(0.002 kg)*(260 m/s)^2 = Fav*(0.43 m)
In your case, the distance is the gun barrel length. Distance must be in meters to get the force in Joules.
Solve the above equation for Fav, the average force.
A 2.0 g bullet leaves the barrel of a gun at a speed of 260 m/s.
(a) Find its kinetic energy.
J
(b) Find the average force exerted by the expanding gases on the bullet as the bullet moves the length of the 43 cm long barrel.
N
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