So say a truck is going down the highway at a constant velocity. If the truck is about to hit a car the force applied to that car from the truck would be it’s (mass)x(acceleration). Since velocity is constant it’s acceleration = 0 so the resulting force would be 0. Obviously this makes no sense so could someone explain this.
Posted Oct 23, 2020, 3:43 AM UTC
Well it is actually the SUM of forces equals mass times acceleration, so even if the acceleration is zero, all that is telling you is that when you add all the forces in your system up they will equal zero. For this specific question it is more intuitive to think in terms of conservation of momentum. The total monentum of the system before the collision has to equal the total momentum of the system after the collision. So the stationary vehicle, as song as it is sufficiently light, will have to have some velocity after the collision so the conservation of momentum isn't violated. To get really detailed, if you are on a highway your truck will be experiencing wind resistance and friction from the road (among the many other sources of friction from the internal workings of the truck), so in order for the truck to have zero accelerarion the engine needs to apply a force equal to all the forces trying to slow the truck down.
up to an instant before the crash there is no acceleration if the truck is moving and say the car is still,the moment they touch each other things must change , the car can't stay still and the truck moving as before.
the truck has inertia so it tries to keep moving, but the car also has inertia and tries to stay in place.
So the truck will make a force on the car and the car will make a Force on the truck until both reach their final speed.
the actual Forces and final speeds of both objects dependof other Factors like the how much eachvehide deforms
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The velocity is constant until it his the car. As soon as it hits the car the velocity changes (the truck slows down), which means there are forces involved