Question

You're driving down the highway late one night at 20 m/s when a deer steps onto the road 35 m in front of you. You reaction time before stepping on the brakes is 0.50 s, and the maximum deceleration of your car is 10 \mathrm { m } / \mathrm { s } ^ { 2 }10m/s 2 . a. How much distance is between you and the deer when you come to a stop

Answer 1

Answer:

Explanation:

Discount the time here; it's not important. It doesn't tell you how long it takes the car to stop, it only refers to reaction time, which means nothing in the scheme of things.

The useful info is as follows:

initial velocity = 20 m/s

final velocity = 0 m/s

a = -10 m/s/s

and we are looking for the displacement. Use the following equation:

$v^2=v_0^2+2a$Δx

where v is the final velocity, v₀ is the initial velocity, a is the deceleration (since it's negative), and Δx is displacement. Filling in:

$0^2=(20)^2+2(-10)$Δx and

0 = 400 - 20Δx and

-400 = -20Δx so

Δ = 20 meters