Itraveled 3.8 miles in 12 minutes. calculate my average velocity in miles per hour. 2) a sprinter increased his/her speed from 18 mph to 28 mph over 3.5 seconds. calculate his/her acceleration.

1) Average velocity: 19 mi/h

The average velocity is given by:

where

d is the displacement

t is the time taken

In this problem,

d = 3.8 mi is the displacement

is the time taken

Substituting,

Note that this is actually the average speed, not the average velocity, since there is no information about the direction of the motion.

2)

The acceleration is given by

where we have

v = 28 mph is the final velocity

u = 18 mph is the initial velocity

t = 3.5 s is the time taken

Conerting the time from seconds to hours,

So the acceleration is

b.a device that inputs heat into a cool object