A 1000kg car moving north at 20m/s collides head-on with an 800kg car moving south at 30m/s.?

Question

If the cars stick together, in what direction and at what speed does the wreckage begin to move?

Answer 1

The law of conservation of momentum holds in this case.

The initial momentum of the system must equal the final momentum of the system.
In this case, we will call the "System" both cars.

Car 1 has a mass (m1) of 1000 kg, velocity (v1) of 20 m/s.
Car 2 has a mass (m2) of 800 kg and a velocity, in what we will call the negative direction, v2 = -30 m/s.

The total momentum (P) does not change.

P = P1 + P2

P1 = m1 * v1 = 1000 kg * 20 m/s
P1 = 20000 kg m/s

P2 = m2 * v2 = 800 kg * -30 m/s
P2 = -24000 kg m/s

P = 20000 kg m/s + -24000 kg m/s
P = -4000 kg m/s

So the resulting 1800 kg mass will have a momentum of -4000 kg m/s, meaning that it will be traveling in the "negative" direction, AKA, South.

P = -4000 kg m/s = 1800 kg * v_f
v_f = -4000 / 1800
v_f = -2.22 m/s

The resulting blob of the two cars which stuck together will be traveling -2.22 m/s South.

Answer 2

Momentum of Northward car = 1000 X 20 = 20000 Kg.m/s
Momentum of Southward car = 800 X 30 = 24000 Kg.m/s

Resultant momentum = 4000 Kg.m/s Southward
Resultant mass = 1800 Kg

Resultant speed = 4000 / 1800 = 2.22 m/s and the wreckage will move southward.

Answer 3

m1v1 = m2v2 (this is a momentum question - mass times velocity) the one with more momentum will continue in its own direction (800 x 30 = 24000 kgm/s, 1000 x 20 = 20000 kgm/s) the first car will basically be a negative on the second. (m1v1 will equal 4000 kgm/s) if they link together, the new mass will be 1800 kg. 4000kgm/s divided by 1800 kg will give a velocity of 2.22 m/s in the south direction

Answer 4

ellastic or inellastic collision? if ellastic, momentum is conserved and you need to state that p1=p2 thus m1v1+m2v2=m3v3 where m1v1 is initial momentum of the 1st car, m2v2 is initial momentum of the 2nd car, and m3v3 is the final momentum of both cars and m3=m1+m2. hope this helps

oh and as far as the direction, since they are both colliding head on, they will continue to move in the same direction as the one with greater initial momentum, with the speed as calculated above.

Answer 5

2.2 m/s moving towards the south. Momentum is conserved regardless of whether the collision was elastic or not, which this collision was obviously inelastic (cars stuck together). What Jesse meant to say was that kinetic energy is not conserved on an inelastic collision.

Answer 6

the wreckage will move south at a decending rate of speed starting at 10m/s and ending in 5 seconds

Answer 7

800kg * 30 m/s - 1000 kg * 20 m/s = 4000 kg*m/s

1000 kg + 800 kg = 1800kg

(4000 kg*m/s) / (1800kg) = 20/9 m/s in the direction of the 800 kg car.

Answer 8

Pretty much all directions.

Answer 9

Not quite sure how to answer this

Answer 10

Wow, thanks! I was wondering the same question today