Moving at 20 m/s , a remote controlled car of mass 1000kg hits a pile of sand and comes to rest in 10 s. Find the average force that acted to stop the car.
The same car now hits a wall and comes to rest in 1s. Find the average force that acted to stop the car.
Use knowledge gained from this problem to explain why airbags generally reduce injuried during a car crash.
Force*time=mass*changevelocity
a) [1000* -20 ]/10 = -2000
b) [1000* -20 ]/1 = -20000
c) Would Airbags reduce injuries because they are a lot softer than a steering wheel. They also allow more time for the head to hit the airbag which will reduce the force.
I'm not sure if I did the change of velocity part right but these are the answers I got and I was wonder if they are correct.
Yes, a, b, c are correct. However, you ought to put units in the answers. Numbers alone are meaningless.
Yes, you are correct in your calculations. The average force that acted to stop the car in scenario a) (hitting a pile of sand) is -2000 N (Newtons), and in scenario b) (hitting a wall) is -20000 N. The negative sign indicates that the force is opposing the motion of the car.
In scenario a), the car took 10 seconds to come to rest, while in scenario b), it took only 1 second. The shorter the time it takes for an object to stop, the greater the force required. This can be seen from the larger force value in scenario b) compared to scenario a) for the same initial velocity and mass.
Now, let's move on to the explanation of why airbags generally reduce injuries during a car crash. When a car comes to a sudden stop due to a collision, the passengers inside the car still continue moving at the same speed they were traveling before the collision. This abrupt deceleration can cause severe injuries, especially if passengers hit hard surfaces like the steering wheel or dashboard.
Airbags in cars are designed to provide a cushioning effect during a collision. They rapidly inflate and provide a soft, padded surface for the occupants to come into contact with. By increasing the duration of the collision and spreading out the force over a longer period of time, airbags help to reduce the impact force experienced by the occupants.
The extended duration of contact with the airbag allows the passenger's body to decelerate more gradually, reducing the force exerted on their body. This can help to prevent or minimize injuries such as head or chest trauma that can occur when the body strikes hard surfaces directly.
In summary, airbags reduce injuries during a car crash by increasing the time it takes for the occupants to come to a stop, thus reducing the overall force exerted on their bodies.