The brakes of a car moving at 14m/s are suddenly applied and the car stops 4s later
A. What is the cars acceleration?
B. How long will it take the car to stop, starting from 20m/s with the same acceleration?
C. How long will it take to slow down from 20 m/s to 10 m/s with the same acceleration?
Here are the answers I got:
A. 3.5 m/s
B. 5.71 s
C. 2.85 s
I think A is correct but I'm not sure about B and C. Help?
2007-04-03 14:15:54 · 3 answers · asked by tu madre 1 in Science & Mathematics ➔ Physics
Yep, you got everything right (although I think you may have rounded wrong on part C, but my windows calculator is corrupted so I can't use it to check, but it sounds right!)
Good job ;)
2007-04-03 14:20:03 · answer #1 · answered by pedros2008 3 · 0⤊ 0⤋
The answer to A should be - 3.5 m/s^2 (note the negative : it means deceleration). If the number is positive, the car is not slowing down to a stop but rather speeding up. The question did ask for the car's ACCELERATION.
The other answers are correct though C should be 2.86 s.
Are you using significant figures in these calculations or haven't you reached that yet in this course?
2007-04-03 14:34:19 · answer #2 · answered by flandargo 5 · 0⤊ 0⤋
everything is correct but the unit for acceleration is m/s^2, not m/s
2007-04-03 14:27:41 · answer #3 · answered by 7 · 0⤊ 0⤋