- #1
ScienceGeek
- 5
- 0
I am reviewing General Physics for the MCAT and have a question regarding kinematics in one dimension. The question reads as follows:
A speeding motorist traveling 120 km/h passes a stationary police officer. The officer immediately begins pursuit at a constant acceleration of 10.0 km/h/s. How much time will it take for the police officer to reach the speeder, assuming that the speeder maintains a constant speed? How fast will the police officer be traveling at this time?
I am unsure how to solve this problem, conceptually speaking. I converted the mixed units to units compatible with m/s. My calculated values are as follows:
Vmotorist = 33 m/s
V0cop = 0 m/s
V cop = ?
Acop = 2.8 m/s2
T = ?
I have used the following kinematics equations:
V2 = V02 + 2a∆X
V = V0 + aT
X = X0 + V0T + ½ aT2
I calculated the time it would take the cop to reach 33 m/s and the distance at that time:
V= V0 + aT X = X0 + V0T + ½ aT2
33 m/s = (2.8 m/s2)*t = ½ * 2.8 * 11.82
T = 11.8 s = 194.9 m
I also calculated the difference in distance between the motorist and the cop at this point (194.5 m) however I am unsure as to whether or not these values are even relevant. Any assistance with the direction I should go into solve these questions would be greatly appreciated. Thank you!
A speeding motorist traveling 120 km/h passes a stationary police officer. The officer immediately begins pursuit at a constant acceleration of 10.0 km/h/s. How much time will it take for the police officer to reach the speeder, assuming that the speeder maintains a constant speed? How fast will the police officer be traveling at this time?
I am unsure how to solve this problem, conceptually speaking. I converted the mixed units to units compatible with m/s. My calculated values are as follows:
Vmotorist = 33 m/s
V0cop = 0 m/s
V cop = ?
Acop = 2.8 m/s2
T = ?
I have used the following kinematics equations:
V2 = V02 + 2a∆X
V = V0 + aT
X = X0 + V0T + ½ aT2
I calculated the time it would take the cop to reach 33 m/s and the distance at that time:
V= V0 + aT X = X0 + V0T + ½ aT2
33 m/s = (2.8 m/s2)*t = ½ * 2.8 * 11.82
T = 11.8 s = 194.9 m
I also calculated the difference in distance between the motorist and the cop at this point (194.5 m) however I am unsure as to whether or not these values are even relevant. Any assistance with the direction I should go into solve these questions would be greatly appreciated. Thank you!