Question

4.) It was once recorded that a Jaguar left skid marks which were +300 m in length.

Answer 1

Answer:

Initial velocity of the jaguar: 49 $\frac{m}{s^2}$  (answer d)

Explanation:

Considering that this uniformly accelerated problem (with negative acceleration since the jaguar was reducing its velocity to full stop), does not include the time the jaguar was skidding , we can use the kinematic equation that doesn't include time, but relates velocities (initial and final) with the acceleration ($a$), and the distance "D" covered during the accelerated motion:

$v_f^2-v_i^2=2\,a\,D$

For our problem, the initial velocity ($v_i$ is our unknown, the final velocity is zero ($v_f = 0$ - since the jaguar stops in the process),  the negative acceleration is given as $a=-4\,\frac{m}{s^2}$, and the distance D of the skid marks is said to be 300 m in length. Therefore:

$v_f^2-v_i^2=2\,a\,D\\0-v_i^2=2\,(-4)\,(300)\\v_1^2=2400\\v_1=\sqrt{2400} \\v_1=48.99\,\frac{m}{s^2}$

Which we can round to 49 $\frac{m}{s^2}$