Leroy, who has a mass of 100kg , is skateboarding at 8.4m/s when he smacks into a brick wall and comes to a dead stop in 0.2 s.

Find his deceleration.
Find the force of impact. (ouch!)

To find Leroy's deceleration, we can use the equation for acceleration:

acceleration = (final velocity - initial velocity) / time

Given that Leroy's initial velocity (u) is 8.4 m/s, his final velocity (v) is 0 (since he comes to a dead stop), and the time (t) is 0.2 s, we can substitute these values into the equation:

acceleration = (0 - 8.4) / 0.2

acceleration = -8.4 / 0.2

acceleration = -42 m/s^2

Therefore, Leroy's deceleration is -42 m/s^2.

To find the force of impact, we can use Newton's second law of motion:

force = mass * acceleration

Given that Leroy's mass (m) is 100 kg, and his acceleration (a) is -42 m/s^2, we can substitute these values into the equation:

force = 100 kg * (-42 m/s^2)

force = -4200 N

However, since force is a vector quantity, the negative sign indicates that the force is acting in the opposite direction of Leroy's motion. Thus, we can say that the force of impact is 4200 N in the opposite direction of Leroy's initial motion.

Now, it's important to note that force can cause injury or damage, but the severity of the impact also depends on how the force is distributed. The specific effects on Leroy's body and the resulting injury will depend on various factors such as the duration of impact and the distribution of forces within his body.