Physics
posted by Richard .
Having trouble determ the formulas for the follow problems.
2. If an automobile travels at 30 km/hr. for 2 hours, how far does it go?
60 km
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?
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?

Let D = distance travelled and Vo be the initial velocity, and a be the acceleration
2. D = Vo * t (no acceleration; V remains Vo)
3. D = Vo*t + (1/2) a t^2
Vo = 8 1/3 m/s ; answer will be in meters
4. Vfinal^2 = Vo^2 + 2 a D
Vfinal = Vo + a t,
but you need to solve for t to use the second formula. The two formulas are consistent.