A 30g bullet with a horizontal velocity of 500m/s comes to a stop 12 cm within a solid wall.
a) what is the change in its mechanical energy?
b) What is the magnitude of the average force from the wall stopping it?
a) what would I use of the equation? Can you please explain what i would do? I am confused
b)Would I use F= ma?
a) The original mechanical energy is the kinetic energy. It goes from
(1/2) M Vo^2 to zero. Vo is the initial velocity, 500 m/s
b) (average Force) x (stopping distance) = mechanical energy loss
Solve for the average force
a) To find the change in mechanical energy, you need to determine the initial kinetic energy (KE) of the bullet and its final kinetic energy. The initial KE can be calculated using the formula:
KE = (1/2) mv^2
Where:
m = mass of the bullet = 30 g = 0.03 kg
v = initial velocity of the bullet = 500 m/s
Substituting the values, we have:
KE = (1/2) (0.03 kg) (500 m/s)^2
To find the final kinetic energy, we need to recognize that the bullet comes to a stop, which means its final velocity is 0 m/s. Therefore, the final KE is 0.
The change in mechanical energy is then given by:
Change in KE = Final KE - Initial KE
Since the final KE is 0, the change in mechanical energy is simply the negative value of the initial KE.
b) To find the average force exerted by the wall to stop the bullet, you can use the formula:
Force = Change in mechanical energy / Stopping distance
Therefore, the average force can be calculated by dividing the change in mechanical energy (which you obtained in part a) by the stopping distance (12 cm = 0.12 m).
Average Force = (Change in KE) / Stopping distance