Car 1 was sitting at rest when it was hit from the rear by...

Car 1 was sitting at rest when it was hit from the rear by car 2 of identical mass. Both cars had their breaks on and they skidded together 6 m in the original direction of motion. If the stopping force is ~ 0.7 ´ (combined weight of the cars) , i.e., µ = 0.7, find the approximate speed of car 2 just before the collision took place

Transcript

00:01 In this problem, two car of radical mass, car 1 and car 2, car 1 is initially at rest.

00:09 We consider its initial speed as u1, that is 0, and the car 2 is in motion and it has an initial speed of u2.

00:18 After the collision, they stuck together and move with a common speed.

00:23 Let's say v.

00:24 This is car 1 and this is car 2.

00:29 Now we have the force on if we consider for car 1 and 2 after collision.

00:46 If we draw the force diagram along the direction of motion, the only force act on the car is the resistive force and that is equivalent to 0 .7 times of its weight.

01:00 Okay, okay? so we can calculate the acceleration.

01:06 So from newton's second law of motion, the summation of the summation of all.

01:09 Forces along the x direction is equivalent to the mass times the acceleration.

01:16 So along the x direction the force is 0 .7 times the weight or you can say the mass of the card that is the total mass of the combined car will be 2m times g and that will be equivalent to consider this direction as positive direction so this will be negative and that will be equivalent to 2m times the acceleration.

01:38 Therefore, the acceleration of the car after the collision is equivalent to minus 0 .7 times the gravity is an acceleration.

01:47 Okay.

01:49 Now, from this we can calculate the speed of the curve 1 and 2 after the collision...

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