# Physics,Question ,Solved but about Units?

posted by on .

These are “plug-in-the-number” tasks to familiarize you with the
main formulas that link the physics concepts of this chapter. They
are one-step substitutions, much less challenging than the Think
and Solve problems that follow.
Average speed !
total distance covered
travel time
34. Show that the average speed of a rabbit that runs a distance
of 30 m in a time of 2 s is 15 m/s.

35. Calculate your average walking speed when you step
1.0 m in 0.5 s.
Acceleration !
change of velocity
time interval
!
"v
"t
Here is the example practice question but Im not sure how to work it out,perhaps this is more specific?
Physics - Steve, Wednesday, October 10, 2012 at 2:25pm
keep in mind that if there is very little data provided, the formulas involved will be relatively simple.

Always keep track of the units. That way you will know whether you are manipulating the various quantities correctly.

#34.
speed is distance/time. so, since you are given a distance and a time,

speed = 30m/2s = 30/2 m/s = 15m/s

#35.
1.0m/0.5s = 1/.5 m/s = 2m/s

as for acceleration, just as speed is change in distance over elapsed time, acceleration is change in speed over elapsed time.

So, if a runner increases his speed from 10m/s to 20m/s in 2 seconds, the acceleration a is

a = (20-10)m/s / 2s = 10/2 m/s^2 = 5m/s^2
How do I keep track of the Units?