Question

As shown in the figure below, a skateboarder starts at point A on the ramp and rises to point B, a maximum height of h = 2.13 m above the top of the ramp. If the amount of work done against friction is insignificant, determine his initial speed at point A.

Answer 1

His initial speed at point A which will be given as :

using conservation of energy, we have

$\Delta$K.E = $\Delta$P.E

(1/2) m v₀² = m g h

v₀ = _$\sqrt{}$2 g h

where, g = acceleration due to gravity = 9.8 m/s²

h = maximum height above the top of ramp = 2.13 m

then, we get

v₀ = _$\sqrt{}$2 (9.8 m/s²) (2.13 m)

v₀ = _$\sqrt{}$41.748 m²/s²

v₀ = 6.46 m/s