A bullet of mass 0.05kg has a speed of 400cm|s. What is its kinectic energy? It hits a wall of which the average resistive force is 1000N, Cal.the distance penestrated by the bullet

KE=1/2 m v^2= 1/2 .05*4^2 Joules

distance=KE/force

To calculate the kinetic energy (KE) of the bullet, we can use the formula:

KE = 1/2 * m * v^2

Where:
m = mass of the bullet
v = velocity of the bullet

In this case, the mass of the bullet (m) is given as 0.05 kg and the velocity (v) is given as 400 cm/s.

First, we need to convert the velocity to meters per second (m/s) as the units of mass are in kilograms. Since 1 m = 100 cm, we can divide the velocity by 100 to convert it to m/s:

v = 400 cm/s * (1 m/100 cm)
v = 4 m/s

Now we can substitute the values into the formula:

KE = 1/2 * 0.05 kg * (4 m/s)^2
KE = 1/2 * 0.05 kg * 16 m^2/s^2
KE = 0.4 J

Therefore, the kinetic energy of the bullet is 0.4 joules.

Now, let's move on to calculating the distance penetrated by the bullet using the resistive force.

The work done by a force can be calculated using the formula:

Work = Force * Distance

Since the average resistive force is given as 1000N, and we need to find the distance penetrated (d), we rearrange the formula as:

Distance = Work / Force

To find the work done, we need to calculate the change in kinetic energy since the bullet comes to rest after penetrating the wall.

Work = Change in KE

In this case, the change in kinetic energy can be calculated by subtracting the initial kinetic energy from the final kinetic energy, which is zero.

Change in KE = Final KE - Initial KE
Change in KE = 0 J - 0.4 J
Change in KE = -0.4 J

The negative sign indicates the work done against the resistive force.

Now we can calculate the distance penetrated:

Distance = -0.4 J / 1000 N
Distance = -0.0004 m

Since distance cannot be negative, we take the absolute value of the result:

Distance = |-0.0004 m|
Distance = 0.0004 m

Therefore, the distance penetrated by the bullet is 0.0004 meters.