Answer:
v = 0.6c = 1.8 x 10⁸ m/s
Explanation:
From Einstein's theory of relativity, we know that the length of an object contracts while traveling at a speed relative to speed of light. The contraction is according to following equation:

where,
L = Relative Length
L₀ = Rest Length
According to given:
L = 0.8 L₀
c = speed of light = 3 x 10⁸ m/s
v = relative speed of train = ?
Therefore,

squaring on both sides:

taking square root on both sides:
<u>v = 0.6c = 1.8 x 10⁸ m/s</u>
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Answer:
D) 735 J(oules)
Explanation:
Work is defined as force * distance
Force is defined as mass * acceleration
Given a mass of 15 kg and a gravitational acceleration of 9.8 m/s² since the box is being lifted up, the force being applied to the box is 15 kg * 9.8 m/s² = 147 N
Since the distance is 5 meters, the work done is 147 N * 5 m = 735 N/m = 735 J, making D the correct answer.
Answer:
yes
Explanation:
because motion is relevant
Answer:
the work done by the 30N force is 4156.92 J.
For this problem, they don´t ask you to determine the work of the total force applied in the block. They only want the work done for the force of 30N, with an angle of 30º respectively of the displacement and a traveled distance of 160m. So:
W=F·s·cos(α)=30N·160m·cos(30º)=4156.92J