You construct a mobile out of four objects, a sphere, a pyramid, an ellipsoid, a

Question

You construct a mobile out of four objects, a sphere, a pyramid, an ellipsoid, and a cube. The mobile is in equilibrium in the configuration shown below, where the vertical dashed lines are 20 cm apart. The mass of the strings (in blue) and rods (in red) can be neglected. If the pyramid has a mass of 280 g, what is the mass of each of the other objects? See if you can do this problem without a calculator.

(a) What is the mass of the ellipsoid?
g

(b) What is the mass of the cube?
g

(c) What is the mass of the sphere?
g

PLEASE HELP! :( and explain and answer all parts!

Explanation / Answer

a)

here

the sum of torques is zero

me * g * 3*r - mc * g * r = 0

then

mp * g * 3r - ( me + mc) *g * 3r

me = me + 3*me = 4me

me = mp /4

me = 280 / 4 = 70 gram

b)

mc = 3 * me

mc = 3 * 70 = 210 gram

c)

T = (mp + me + mc ) * g = 4*me + me + 3*me ) *g = 8me *g

now we use the sum of torques is zero and say ms is the mass of the sphere

ms * g * 2*r - 8 *me * g * 3r = 0

ms = 12 * me = 12 * 70 = 840 gram

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.