A car runs off the road and hits a stationery rock. Some glass pieces from the windscreen are projected forward and were found at an average distance of 15 meters from the car. The average height of the windscreen is 1.5 meters. Calculate the speed of the car at the time of impact.
first, that's stationary, since the rock is presumably not made of paper.
How long does it take the glass to fall 1.5 meters?
Then figure the horizontal speed using speed = distance/time.
0.5sec
16m/s
To calculate the speed of the car at the time of impact, we can use the principle of conservation of linear momentum. The linear momentum of an object is given by the product of its mass and velocity.
In this scenario, we need information about the mass of the car, the mass of the glass pieces, and the distance traveled by the glass pieces. Without this information, it is not possible to directly calculate the speed of the car at the time of impact.
However, we can make some assumptions and estimate a rough value based on the given information. Let's assume the mass of the car is 1000 kg (a common estimate for an average-sized car) and the mass of the glass pieces is negligible compared to the car.
To calculate the velocity of the car, we use the equation:
linear momentum = mass x velocity
The initial linear momentum of the car, before the impact, is zero because it was not moving. After the impact, the linear momentum of the car is given by:
final linear momentum = mass of car x velocity of car
Since the glass pieces were projected forward, we can assume that they gained velocity due to the impact. We can use the average distance traveled by the glass pieces to estimate the final velocity of the car.
First, we convert the average distance of 15 meters to the time taken to travel that distance. We can use the formula:
distance = velocity x time
Assuming the glass pieces travel horizontally, we can ignore the effect of gravity, and the vertical component of the glass pieces' motion can be neglected. Therefore, the time taken to travel 15 meters can be calculated as:
time = distance / velocity = 15 meters / velocity
Next, we can substitute this time value into the equation of final linear momentum to obtain:
final linear momentum = mass of car x velocity of car
Since the linear momentum is conserved, we can equate the initial and final linear momentum:
0 = mass of car x velocity + mass of glass pieces x velocity
Since we assumed the mass of the glass pieces to be negligible compared to the car, we can ignore the second term:
0 = mass of car x velocity
Solving this equation for velocity, we find:
velocity = 0 m/s
Therefore, based on the assumptions made, the estimated speed of the car at the time of impact is zero. However, please note that this is a rough estimation, and without additional information, it is difficult to provide a more accurate calculation.