Physics
posted by Emma .
Could you please check my answers and units. Thanxs!
1. An automobile starts from rest and accelerates at 3m/s2 for 4 seconds. How fast is it going after acceleration?
I got 12 m/s
3. At time = 0 an automobile already traveling at 30 km/hr. accelerates at 3m/s2 for 2 seconds. During these two seconds, how far does it go?
I got 12 m/s
4. An automobile is traveling at 30 km/hr. It accelerates at 3 m/s2 until it has covered 100 meters.. What is its new velocity?
 6030 (not sure about units)

3. Change 30km/hr to m/s
30km/hr*1hr/3600sec*1000m/km
then
distance=vi*t + 1/2 at^2 
4. You need to work the units. Chang 30km/hr to meters/second. Then work it, keeping the units in the problem until you find out what your answer is, numerically, and the units.

I am still not understanding. Like for number 3, this is as far as I got 30km/36000000. Then for number 4, would it be similar as to number 3? Also, did I get number 1 correct?