An object with mass m = 20 kg, is moving with V = ct (constant velocity) on the distance d = 60 m on a horizontal surface. The friction coefficient is μ = 0.45. Force applied to the object makes an angle ά = 30° with the horizontal.
find out:
a) the force applied to the object;
b) the mechanical work, made by force of traction upon the object (g = 10 m / s2)
Solution
a) the force applied to the object:
F = m (a + μg) / cos ά + μ * sin ά
we know that a = constant
=> F = μmg / cos ά + μ *sin ά
=> F = 0,45 * 20 * 10 m / s2 / cos 30o + 0,45 * sin 30o
=> F = 0,45 * 20 * 10 m / s2 / √3/2 + 0,45 * 0,5
=> F ≈ 83 N (newton)
b) the mechanical work, made by force of traction upon the object (g = 10 m / s2):
L = F * d * cos ά
L = 83 N * 60 m * cos 30o
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