Physics Help - Average velocity / Magnitude.?

Question

A car makes a 60.0 km trip with an average velocity of 40.0 km/h in a direction due north. The trip consists of three parts. The car moves with a constant velocity of 24 km/h due north for the first 15 km and 65 km/h due north for the next 32 km. With what constant velocity (magnitude and direction) does the car travel for the last 13 km segment of the trip?

I'm confused on what to do.

Any help is greatly appreciated!

Answer 1

Avg. velocity is 40 km/h over 60 km (1.5 hours)

since the trip is 60 km due North, with the given distances (15 km, 32 km, and 13 km) adding up to 60 km, and all the velocities given so far are due North, it is known that the final leg of the journey is due North, and therefore a simple equation can be set up, converting distance and velocity to times using the equation--> distance = velocity * time:

(15 km / 24 km/h) + (32 km / 65 km/h) + (13 km / x km/h) = 1.5 h

x = 33.9698 km/h

or ~ 34 km/h due North

Answer 2

Ok

The actual calculating for this question is easy once you know what to do.

The direction is easy because the average is due north

and the parts are due north

so the last part most be due north.

Velocity = distance/time

you have the distance 13km

you just need time

the total trip is 60 km divide 40 km/h so the total time is

1.5 hours

so now you have to subtract the times from the first two parts

time of first part 15/24

time of the second part 65/15

whatever is left is the time of the last part

you just punch that into the velocity equation

this method will give you velocity in km/h

they might want it in m/s so you might have to do that

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what ever time is left punch that into the velocity equation