In a court hearing, a police expert reconstructs an accident in the following wa
ID: 1643122 • Letter: I
Question
In a court hearing, a police expert reconstructs an accident in the following way (Fig. 9-4): A sports car of mass m_1 = 1000 kg collided with a parked pickup truck of mass m_2 = 1500 kg. From the skid marks, it is estimated that the speed of the pickup immediately after the collision was 21.6 m/s at an angle of 33.7 degree with the direction of the road. The sports car left a mark at an angle of 60 degree with the road but did not stop, leaving the scene badly damaged. Can the expert determine from these data if the sports car was speeding and its driver fully responsible?Explanation / Answer
yes, initial Speed of car can be found and then it can be compared with maximum speed limit whether he is guilty or not.
Applying momentum conservation for the collision,
Along y direction,
momentum before collison = momentum after the collision
0 = (1500)(21.6 sin33.7) - (1000)( v sin60)
v = 20.76 m/s
Along x direction,
1000 v0 = (1500)(21.6 cos33.7) + (1000)(20.76cos60)
v0 = 37.3 m/s .........Ans