Question

. Maria walked 1.5 miles south to her house in 0.5 hours. What is her speed in miles per hour?

What is her velocity in meters per second?

Answer 1

1) 3 miles/Hour

The speed is defined as the distance covered divided by the time taken:

`v=(d)/(t)`

where

d = 1.5 mi is the distance

t = 0.5 h is the time taken

Substituting,

`v=(1.5)/(0.5)=3 mi/h`

2) 1.34 m/s south

Velocity, instead, is a vector, so it has both a magnitude and a direction. We have:

`d=1.5 mi \cdot 1609 m/mi = 2414 m` is the displacement in meters

`t=0.5 h \cdot 3600 s/h =1800 s` is the time taken in seconds

Substituting,

`v=(2414 m)/(1800 s)=1.34 m/s`

And the direction of the velocity is the same as the displacement, so it is south.