Velocity,time,acceleration question

  • Thread starter Thread starter drinkingstraw
  • Start date Start date
AI Thread Summary
A blue car travels at a constant speed of 10 m/s for 12 seconds, covering a distance of 120 meters. In contrast, a police car starts from rest and accelerates at 4 m/s² for 3 seconds, reaching a speed of 12 m/s and covering 18 meters during that time. After 3 seconds, the police car continues at a constant speed of 12 m/s. To determine when the police car passes the blue car, the distances traveled by both vehicles must be equated. The problem emphasizes the importance of calculating distance over time to find the point of intersection.
drinkingstraw
Messages
23
Reaction score
0
A blue car moving at constant speed of 10m/s passes a polic car that is at rest. The police car accelerates from rest at 4m/s^2 for 3.0 seconds and then maintains a constant speed. The blue car maintains constant speed for the entire 12 seconds. When does the police car pass the blue car?

Calculations:
Blue Car:
Vi= 10 m/s
Vf = 10 m/s
deltaT = 12 s
deltaD = 120 m
acceleration = 0

Police Car:
Vi = 0m/s
acceleration = 4m/s^2 (for the first 3 seconds)
deltaD (for first three seconds) = 18 m
Vf = 12 m/s

So when the deltaD of the blue car = the deltaD of the police car, the police car is at the same distance as the blue car.

How would I go about doing this?
 
Physics news on Phys.org
Note how this problem is similar to this question.
Probably if you solve the other one, you will be able to do this one yourself.
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top