Question

An air puck of mass 0.028 kg is tied to a string
and allowed to revolve in a circle of radius 1.1
m on a frictionless horizontal surface. The
other end of the string passes through a hole
in the center of the surface, and a mass of 1.9
kg is tied to it, as shown in the figure. The
suspended mass remains in equilibrium while
the puck revolves on the surface.
The acceleration of gravity is 9.81 m/s2 .a) What is the magnitude of the force that
maintains circular motion acting on the puck?
Answer in units of N.
b) What is the linear speed of the puck? Answer in units of m/s.

Answer 1

The weight of the suspended mass (M) provides the central force that maintains the circular motion of the puck.

Centripetal force = mv²/r where m = mass of puck and r the radius of motion, v is the tangential speed.


Mg = mv²/r

Magnitude of force = Mg = 1.9 X 9.81 = 18.64 N

(b) mv²/r = 18.64

v² = 18.64r/m

= (18.64 X 1.1) / 0.028

= 732.29

v = √732.91
= 27.1

Linear speed of puck is 27.1 m/s.

Is this correct??

Answer 2

yes it is correct