A bullet moves east at a velocity of 480 m s⁻¹ - NSC Physical Sciences - Question 4 - 2019 - Paper 1

To calculate the mass of the bullet, we use the formula for momentum, which is given by: $p = mv$ Where:

• $p$ is the momentum (24 kg·m s⁻¹)
• $m$ is the mass of the bullet
• $v$ is the velocity of the bullet (480 m s⁻¹)

Rearranging the formula gives: $m = \frac{p}{v} = \frac{24}{480} = 0.05 ext{ kg}$

The net force on the bullet can be calculated using Newton's second law, which states: $F_{net} = ma$ Where:

• $F_{net}$ is the net force
• $m$ is the mass of the bullet (0.05 kg)
• $a$ is the average acceleration of the bullet through the block.

To find acceleration ($a$), we use the formula: $a = \frac{(v_f - v_i)}{t}$ Where:

• $v_f$ is the final velocity (80 m s⁻¹)
• $v_i$ is the initial velocity (480 m s⁻¹)
• $t$ is the time (0.01 s)

Calculating $a$: $a = \frac{(80 - 480)}{0.01} = -40000 ext{ m/s}^2$

Now substituting into the force equation: $F_{net} = (0.05)(-40000) = -2000 ext{ N}$

The magnitude of the average net force exerted by the wooden block on the bullet is 2000 N.