They are unproven but accepted as fact.
Many experiments support them but they can be disproven by the results of a single experiment. Until then, they stand.
The third statement is correct.
Yes, acceleration only tells you how velocity is changing. It doesn't say anything about what velocity is at any given time.
For example, if you set your car to cruise control on the highway going 80 mph. That is a constant high velocity, yet the car has 0 acceleration.
The opposite is also true. After a red light turns green, you put foot on the gas to accelerate. However, your velocity is initially low even though it has high acceleration.
Answer:
37.7m/s: principle of conservation of momentum
Explanation:
The principle to make use of is the principle of conservation of momentum which States that the sum of momentum of bodies before collision is equal to the sum of momentum of bodies after collision. This bodies will move with the same velocity after collision.
Momentum = Mass × velocity
For car of mass 2200kg moving with velocity 33m/s:
Momentum of car before collision = 2200×33
= 72,600kgm/s
For the truck of mass 4500kg;
Momentum = 4500 ×(22-(-18)
= 4500×40
= 180000kgm/s
After collision, their momentum is:
Momentum after collision = (2200+4500)v
= 6700v
Using the principle above to get the common velocity v we have
72600+180000 = 6700v
252600 = 6700v
v = 252600/6700
v = 37.7m/s
