Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

(a) Standing above the North Pole and looking down at the earth, which way is th

ID: 1636126 • Letter: #

Question

(a) Standing above the North Pole and looking down at the earth, which way is the earth rotating: clockwise or counterclockwise? (b) Same question, but standing above the South Pole: clockwise or counterclockwise? A mass m hangs from a massless but amazingly strong string suspended from an elevator which is accelerating up at 9 g. What is the tension in the string in terms of m and g? Two particles in uniform circular motion in a zero-gravity environment, each with mass 3 kg, are connected by a string of length 4 meters. If both particles have tangential speed v = 5 m/s. w hat is the tension in the string in New tons?

Explanation / Answer

As the mass hangs from elevator we consider elevator as the frame of reference.

When the elevator accelerating up at 9g, then a pseudo force (m.9g=9mg) act downward with the gravitational force mg.

So forces on the mass m are:

a) mg downward (gravitational)

b) 9mg downward (pseudo)

Total downward force on the mass m is

=(mg+9mg)

=10mg

This total downward force is equal to the tension in the string.

So tension in string is T=10mg