Question

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

Assuming that the Jaguar skidded to a stop with a uniform acceleration of -4.00 m/s,
determine the velocity of the Jaguar before it began to skid.
a.) 49 m/s
b.) 60 m/s2
c.) 10 m/s
d.) 49 m/s?

Answer 1

Initial velocity of the jaguar: 49
`(m)/(s^2)` (answer d)

Step-by-step 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\,(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=√(2400) \\v_1=48.99\,(m)/(s^2)`

Which we can round to 49
`(m)/(s^2)`