Physics HW help?

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A 4.8 kg object is suspended by a string from the ceiling of an elevator.

Acceleration of gravity= 9.8 m/s^2

a) Determine the tension in the string if it is accelerating upward at a rate of 0.8 m/s^2.

b) Determine the tension in the string if it is accelerating downward at a rate of 0.8 m/s^2.

Answer in units of N.

2007-09-27 16:16:16 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Physics

2 answers

F=W-f
W=mg
f= ma

F= mg - ma= m(g-a)

a) F=m(g - (-a))
F= 4.8(9.8 + 0.8)=50.9N

b) F=m(g-a)
F= 4.8(9.8 - 0.8)
F=43.2 N

2007-09-29 16:22:09 · answer #1 · answered by Edward 7 · 0⤊ 0⤋

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Good Luck,
Blue

2007-09-29 16:22:37 · answer #2 · answered by Blue 4 · 0⤊ 0⤋