Question

1. if you throw a 0.4 kg ball at a speed of 20 m/s, what is the balls kinetic energy?

$m=0.4\\ kg$ $v=20\\ m/s$
$ke=\frac{1}{2}mv^2=\frac{(0.4\\ kg)(20)}{2}=4)$

1. a car with a mass of 900 kg is travelling at a speed of 25 m/s. what is the kinetic energy of

$m=900\\ kg$ $v=25\\ m/s$
$ke=\frac{1}{2}mv^2=\frac{(900)(25)}{2}=225)$

Explanation:

Step1: Recall kinetic energy formula

The formula for kinetic energy is $KE = \frac{1}{2}mv^2$, where $m$ is mass in kg, $v$ is speed in m/s.

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For the 0.4 kg ball:

Step2: Substitute values into formula

$m=0.4\ \text{kg}$, $v=20\ \text{m/s}$
$KE = \frac{1}{2} \times 0.4 \times (20)^2$

Step3: Calculate step-by-step

First compute $(20)^2 = 400$, then $\frac{1}{2} \times 0.4 = 0.2$
$KE = 0.2 \times 400 = 80$

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For the 900 kg car:

Step2: Substitute values into formula

$m=900\ \text{kg}$, $v=25\ \text{m/s}$
$KE = \frac{1}{2} \times 900 \times (25)^2$

Step3: Calculate step-by-step

First compute $(25)^2 = 625$, then $\frac{1}{2} \times 900 = 450$
$KE = 450 \times 625 = 281250$

Answer:

Kinetic energy of the ball: $80\ \text{J}$
Kinetic energy of the car: $281250\ \text{J}$