seeing a police officer ahead and not being sure of the speed limit, a driver slows from 65 mi/hr to 55 mi/hr in 4.0 seconds, trying not to make it obvious. what is the cars acceleration

Respuesta :

Answer:

[tex]-1.13 m/s^2[/tex]

Explanation:

The acceleration of an object is given by:

[tex]a=\frac{v-u}{t}[/tex]

where

v is the final velocity

u is the initial velocity

t is the time it takes for the velocity to change from u to v

For this problem, first we have to convert the velocities of the car from mph to m/s:

[tex]u = 65 mi/h \cdot \frac{1609 m/mi}{3600 s/h}=29.1 m/s[/tex]

[tex]v = 55 mi/h \cdot \frac{1609 m/mi}{3600 s/h}=24.6 m/s[/tex]

While the time interval is

t = 4.0 s

Substituting, we find the acceleration:

[tex]a=\frac{24.6-29.1}{4.0}=-1.13 m/s^2[/tex]