You slam on the brakes of your car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, under identical conditions?

Respuesta :

Answer:

So the car would skid 4 times the initial skidding displacement under the identical conditions when the car's initial velocity is just double.

Explanation:

Under identical conditions when the brakes are applied for the same body moving with twice the initial speed then we can analyse using the equation of motion.

Initially:

[tex]v^2=u^2-2a.s[/tex]

[tex]\Rightarrow s=\frac{u^2}{2a}[/tex] ...........................(1)

where:

[tex]v=[/tex] final velocity of the car = 0 (because the car stops)

[tex]u=[/tex] initial velocity of the car

[tex]a=[/tex] acceleration of the car (here it is deceleration and hence taken with negative sign)

[tex]s=[/tex] displacement of the car before stopping

Final condition:

Initial velocity is, [tex]2u[/tex]

So,

[tex]v^2=(2u)^2-2a.s'[/tex]

[tex]0^2=4u^2-2a.s'[/tex]

[tex]s'=\frac{4u^2}{2a}[/tex]

[tex]s'=\frac{2u^2}{a}[/tex] .............................(2)

Now divide eq. (2) by (1)

[tex]\frac{s'}{s}=4[/tex]

So the car would skid 4 times the initial skidding displacement under the identical conditions when the car's initial velocity is just double.