a 2000-kg car traveling at 8 m/s strikes a stationary car whose mass is the same. The two cars stick together after the crash. What is their speed just afterward?
the speed of the two cars vary, but in your case if it is a 2000-kg car their speed just afterward is 2059 miles per hour.
6 miles
To find the speed of the two cars just after the crash, we can use the principle of conservation of momentum. According to this principle, the total momentum before the crash should be equal to the total momentum after the crash.
The momentum of an object is calculated by multiplying its mass by its velocity. So, the momentum before the crash can be calculated as the product of the mass of the first car (2000 kg) and its velocity (8 m/s):
Momentum before = mass of first car * velocity of first car
= 2000 kg * 8 m/s
= 16,000 kg m/s
Since the cars stick together after the crash, they move with a common final velocity. Let's call this final velocity V. The total momentum after the crash can be calculated as the product of the combined mass of the two cars (2000 kg + 2000 kg = 4000 kg) and their final velocity (V):
Momentum after = combined mass of both cars * final velocity
= 4000 kg * V
= 4000V kg m/s
According to the principle of conservation of momentum, the momentum before the crash should be equal to the momentum after the crash.
Therefore, we can equate the two equations:
16,000 kg m/s = 4000V kg m/s
Now, solving for V:
V = 16,000 kg m/s / 4000 kg
= 4 m/s
So, just after the crash, the two cars will have a speed of 4 m/s.