A 2.10kg mass is attached to a vertical spring with a spring constant of 300N/m
ID: 1381272 • Letter: A
Question
A 2.10kg mass is attached to a vertical spring with a spring constant of 300N/m . A student pushes on the mass vertically upward with her hand while slowly lowering it to its equilibrium position.
a)How many forces do nonzero work on the object?
one
two
three
four
b)Calculate the work done on the object by the gravitational force acting on it as it is lowered into position.
c)Calculate the work done on the object by the spring force acting on it as it is lowered into position.
d)Calculate the work done on the object by the force of the hand acting on it as it is lowered into position.
Explanation / Answer
partA: three forces
use net force F = spring force
mg = kx
where m is mass
g ias accleration due to gravity
k is spring constant
and
x is compression
so
x = mg/k
x = 2.1 * 9.81/300
x = 0.0686 m or 6.86 cm
pa rt B : Work Done by gravitational force W = = Fs
W = 2.1 * 9.8 * 0.0686
W = 1.411 J
---------------------------------
Work Done By spring W = 0.5 kx^2
W = 0.5 * 300 * 0.0686 * 0.686
W = 7.05 J
--------------------------------------
W ork Done by hand = - 1.411 Joules
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