Solving Part (a) of Lamp Mass in Descending Elevator w/ Deceleration of 1.4 m/s2

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SUMMARY

The discussion focuses on calculating the mass of a lamp hanging from a cord in a descending elevator that decelerates at 1.4 m/s². The tension in the cord is given as 56 N. Using the equation T - mg = ma, where T is tension, m is mass, g is gravitational acceleration (9.8 m/s²), and a is the elevator's deceleration, the mass can be determined by rearranging the equation to m = T / (g + a). The correct mass of the lamp is derived from this formula.

PREREQUISITES
  • Understanding of Newton's second law of motion
  • Familiarity with the concepts of tension and gravitational force
  • Basic algebra for rearranging equations
  • Knowledge of acceleration due to gravity (9.8 m/s²)
NEXT STEPS
  • Practice solving similar problems involving tension in different acceleration scenarios
  • Explore the effects of varying gravitational forces on mass calculations
  • Learn about the dynamics of objects in non-inertial reference frames
  • Investigate the implications of tension in cables and cords in engineering applications
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Homework Statement


A lamp hangs vertically from a cord in a descending elevator that decelerates at 1.4 m/s2. (a) If the tension in the cord is 56 N, what is the lamp's mass? (b) What is the cord's tension when the elevator ascends with an upward acceleration of 1.4 m/s2?


Homework Equations


T-mg=ma


The Attempt at a Solution


I got part (b) to be 56 N and that was correct but then I used the formula... but I don't know how to solve for mass for part (a) when there are two masses in the equation above, I know T to be 56N and g to be 9.8m/s squared also a to be 1.4m/s squared... Can anyone help me out? I'm confused.
 
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Just rearrange your initial equation:
T-mg=ma

Thus:
T = mg + ma = m(g +a)

You take it from here.
 

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