Which of these phase changes requires energy?
1 answer:
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Answer:
e. the air mattress exerts the same impulse, but a smaller net avg force, on the high-jumper than hard-ground.
Explanation:
This is according to the Newton's second law and energy conservation that the force exerted by the hard-ground is more than the force exerted by the mattress.
The hard ground stops the moving mass by its sudden reaction in the opposite direction of impact force whereas the mattress takes a longer time to stop the motion of same mass in a longer time leading to lesser average reaction force.
<u>Mathematical expression for the Newton's second law of motion is given as:</u>
............................................(1)
where:
dp = change in momentum
dt = time taken to change the momentum
We know, momentum:
Now, equation (1) becomes:
<em>∵mass is constant at speeds v << c (speed of light)</em>
and,
where: a = acceleration
also
so, more the time, lesser the force.
<em>& </em><u><em>Impulse:</em></u>
∵Initial velocity and final velocity(=0), of a certain mass is same irrespective of the stopping method.
So, the impulse in both the cases will be same.
The speed of the spaceship relative to the galaxy is 0.99999995c.
A light-year measures distance rather than time (as the name might imply). A light-year is a distance a light beam travels in one year on Earth, which is roughly 6 trillion miles (9.7 trillion kilometers). One light-year equals 5,878,625,370,000 miles. Light moves at a speed of 670,616,629 mph (1,079,252,849 km/h) in a vacuum.We multiply this speed by the number of hours in a year to calculate the distance of a light-year (8,766).
The Milky way galaxy is 100,000 light years in diameter.
The galaxy's diameter is a mere 1. 0 ly.
We know that ;
L = 1 light year
L₀ = 100,000 light year
Therefore, the speed of the spaceship relative to the galaxy is 0.99999995c.
Learn more about a light year here:
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