17-Newton's Law Example Problems

17-Newton's Law Example Problems - Phys 211 Feb 23,25 2009...

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Unformatted text preview: Phys 211 Feb 23,25 2009 Newtons Laws Practice Problems Two Masses on a Pulley A frictionless pulley with zero mass is attached to the ceiling, in a gravity Feld of 9.81 m/s 2 . Mass M 2 = 0.10 kg is being accelerated downward at 1.2 m/s 2 . Calculate the mass M 1 1) Identify forces on each mass and acceleration T m 2 g a T m 1 g a Notes: Tension is same all throughout the string acceleration (magnitude) of each mass is the same Two Masses on a Pulley 2) Apply Newtons 2 nd Law T m 2 g a T m 1 g a T m 2 g = m 2 a T m 1 g = m 1 a Note: sign indicates direction! Eliminate T by subtracting equations m 2 g ( m 1 g ) = m 2 a m 1 a m 2 g ( m 1 g ) = m 2 a + m 1 a m 2 g m 2 a = m 1 a + m 1 g isolate m 1 m 2 ( g a ) ( g + a ) = m 1 solve for m 1 m 1 = (0.1 kg )(9.8 m / s 2 ) (0.1 kg )(1.2 m / s 2 ) (9.8 + 1.2 m / s 2 ) = 0.08 kg Pulling Penguins The fgure shows Four penguins that are being playFully pulled along very slippery (Frictionless) ice by a curator. The masses oF three penguins and the tension in two oF the cords are M 1 = 12 kg, M 3 = 16 kg, M 4 = 18 kg, T 1 = 141.13 N and T 2 = 262.00 N. ind the penguin mass that is not given (M 2 ). Force T 2 pulls entire system Force T 1 pulls M1 and M2 Notes: 2 equations and two unknowns: M 2 ,a Eliminate a and solve for M 2 T 2 = ( M 1 + M 2 + M 3 + M 4 ) a T 1 = ( M 1 + M 2 ) a Pulling Penguins Solve for M2 Eliminate a T 2 = ( M 1 + M 2 + M 3 + M 4 ) a T 1 = ( M 1 + M 2 ) a T 2 = ( M 1 + M 2 + M 3 + M 4 ) T 1 ( M 1 + M 2 ) M 2 = (12...
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This note was uploaded on 10/03/2011 for the course PHYS 211 taught by Professor Pettie during the Spring '08 term at South Carolina.

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17-Newton's Law Example Problems - Phys 211 Feb 23,25 2009...

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