Answer:
Correct answer: V = 18.43 m/s
Explanation:
Let be initial velocity (speed) V₀ and the current speed at some point V
At start, the box had kinetic energy which is equal to the total energy.
Ek₁ = E = m v₀²/2 = 40 · 20²/2 = 8,000 J
At the ramp point 3m high the box had potential energy:
Ep = m · g · h = 40 · 10 · 3 = 1,200 J we took that g= 10 m/s²
The total energy at any time is equal :
E = Ek + Ep ⇒ Ek = E - Ep = 8,000 - 1,200 = 6,800 J
Ek = m V²/2 ⇒ V = √2 · Ek/m = √ 2 · 6,800/40 = √340 = 18.43 m/s
V = 18.43 m/s
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