Answer:
64 J
Explanation:
The potential energy change of the spring ∆U = -W where W = work done by force, F.
Now W = ∫F.dx
So, ∆U = - ∫F.dx = - ∫Fdxcos180 (since the spring force and extension are in opposite directions)
∆U = - ∫-Fdx
= ∫F.dx
Since F = 40x - 6x² and x moves from x = 0 to x = 2 m, we integrate thus, ∆U = ∫₀²F.dx
= ∫₀²(40x - 6x²).dx
= ∫₀²(40xdx - 6x²dx)
= ∫₀²(40x²/2 - 6x³/3)
= ∫₀²(20x² - 2x³)
= [20x² - 2x³]₀²
= [(20(2)² - 2(2)³) - (20(0)² - 2(0)³)
= [(20(4) - 2(8)) - (0 - 0))
= [80 - 16 - 0]
= 64 J
Answer:
a. 250kg I think it's the right answer. hope it helps:)
Answer:
The law of reflection (in physics) states that when a light ray is incident on a plane surface, the incident ray, the reflected ray and the “normal” to the surface of the mirror all lie in the same plane. It also states that the angle the incident ray makes with the normal is equal to the angle that the reflected ray makes with the normal.
B because it makes us burn less fossil fuels
