Two cars collide at an intersection. Car A , with a mass of 2000 kg, is going from west to east, while car B, of mass 1500 kg, i
s going from north to south at 15 m/s. As a result, the two cars become enmeshed and move as one. As an expert witness, you inspect the scene and determine that, after the collision, the enmeshed cars moved at an angle of 65∘ south of east from the point of impact. (a) How fast were the enmeshed cars moving just after the collision? (b) How fast was car A going just before the collision?
1 answer:
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Answer:
Explanation:
To solve this exercise it is necessary to take into account the concepts related to gravitational potential energy, as well as the concept of perigee and apogee of a celestial body.
By conservation of energy we know that,
Where,
Replacing
Our values are given by,
Replacing at the equation,
Therefore the Energy necessary for Sputnik I as it moved from apogee to perigee was
Answer:
Approximately .
Explanation:
Let the increase in the rocket's velocity be . Let
represent the initial velocity of the rocket. Note that for this question, the exact value of
doesn't really matter.
The momentum of an object is equal to its mass times its velocity.
- Mass of the rocket with the 5 kg of fuel:
.
- Initial velocity of the rocket and the fuel:
.
- Hence the initial momentum of the rocket:
.
- Mass of the rocket without that 5 kg of fuel:
.
- Final velocity of the rocket:
.
- Hence the final momentum of the rocket:
.
- Mass of the 5 kg of fuel:
.
- Final velocity of the fuel:
(assuming that the the 500 m/s in the question takes the rocket as its reference.)
- Hence the final momentum of the fuel:
.
Momentum is conserved in an isolated system like the rocket and its fuel. That is:
Sum of initial momentum = Sum of final momentum.
.
Note that appears on both sides of the equation. These two terms could hence be eliminated.
.
.
Hence, the velocity of the rocket increased by around 2.5 m/s.