how many work is needed to stop a 20g bullet moving witi speed of 150ms'1
mass = m = 20 g = 20 / 1000 = 0.02 kg
speed = v = 150m/s
The workdone to stop bullet must be equal to its kinetic energy:
W = m v ^ 2 / 2
W = 0.02 * 150 ^ 2 / 2 =
0.02 * 22500 / 2 =
450 / 2 = 225 J
225 Joules
To calculate the work required to stop a bullet, we need to use the formula for work, which is given as:
Work = Change in Kinetic Energy
The kinetic energy (KE) of an object is given by the formula:
KE = (1/2) * m * v^2
Where:
m = mass of the bullet
v = velocity of the bullet
Given:
m = 20 g = 0.02 kg (since 1 g = 0.001 kg)
v = 150 m/s
Step 1: Calculate the initial kinetic energy (KEi) of the bullet.
KEi = (1/2) * m * v^2
KEi = (1/2) * 0.02 kg * (150 m/s)^2
Step 2: Calculate the final kinetic energy (KEf) of the bullet.
Since we want to stop the bullet, the final kinetic energy will be zero.
Step 3: Calculate the change in kinetic energy (ΔKE) of the bullet.
ΔKE = KEf - KEi
ΔKE = 0 - [(1/2) * 0.02 kg * (150 m/s)^2]
Step 4: Calculate the work required (W) to stop the bullet.
W = ΔKE
W = -[(1/2) * 0.02 kg * (150 m/s)^2] (Note: Negative sign indicates work done against the motion)
Now, we can calculate the value numerically:
W = -[(1/2) * 0.02 kg * (150 m/s)^2]
W = -[(1/2) * 0.02 * 22500]
W = -0.225 joules
Therefore, the work required to stop a 20 g bullet moving with a speed of 150 m/s is approximately -0.225 joules. Note that the negative sign indicates that work is done against the motion of the bullet.
To calculate the work needed to stop a bullet, we need to determine the initial kinetic energy of the bullet and the work required to bring it to rest.
First, let's calculate the initial kinetic energy of the bullet using the formula:
Kinetic Energy (KE) = (1/2) * mass * velocity^2
Given:
Mass of bullet (m) = 20g = 0.02 kg
Velocity of bullet (v) = 150 m/s
Plugging in the values:
KE = (1/2) * 0.02 kg * (150 m/s)^2
KE = 22.5 J
Now, since we want to calculate the work needed to stop the bullet completely, we need to consider that the final kinetic energy at rest is zero. Therefore, the work required to bring the bullet to rest is equal to its initial kinetic energy (KE).
So, the work needed to stop the 20g bullet moving at a speed of 150 m/s is 22.5 Joules.