# 101112 - Physics 121 1 F net a= Physics 121 FA B = FB A m 2...

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Unformatted text preview: 11/12/10 Physics 121 1 F net a= 11/12/10 Physics 121 FA B = FB A m 2 FA B where F is either N , T , f , or W T = k s (spring) fA WE 11/12/10 Physics 121 μ AB N A B A = mA g 3 B I net =F net t p = mv p =I 11/12/10 Physics 121 net 4 (mAv A + mB vB ) = 0 m v +m v =m v +m v i AA 11/12/10 i BB f AA Physics 121 f BB 5 Definitions: Kinetic energy = 1 2 mv Work done by a force F = 2 Fx Result ( 1 mv 2 ) = F net x 2 11/12/10 Physics 121 6 F F Work = F|| s = F cos s 11/12/10 s F s F|| Physics 121 7 F|| s F s F In general, for any two vectors that have an angle between them, the dot product is defined to be F F F|| 11/12/10 s = F cos s a b = ab cos a b = a x bx + a y by The dot product is a scalar. Its value does not depend on the coordinate system we select. Physics 121 8 F 11/12/10 r= Physics 121 U 9 ( mv + mgh) = 0 1 2 2 U g = mgh 11/12/10 Physics 121 10 ( mv + kx ) = 0 2 1 2 1 2 U s = kx 1 2 11/12/10 2 2 Physics 121 11 11/12/10 Physics 121 12 11/12/10 Physics 121 13 Mechanical ( 1 mv 2 + mgh + 1 kx 2 ) = 0 2 2 1 2 mv i2 + mghi + 1 kx i2 = 1 mv 2 + mgh f + 1 kx 2 2 2 2 f f 11/12/10 Physics 121 14 11/12/10 Physics 121 15 Energy change Power = time to make the change r W net = =F = F net v (for mechanical work) t t 11/12/10 Physics 121 16 R Position Velocity Acceleration at R vt v R vt at = R v 11/12/10 av = vR Physics 121 v 2 v a= R 17 net F always a= m 2 v in order for the object to move ˆ a= r in a circle with constant speed. R F net v2 Therefore, to do this, ˆ = r we need a net force. m R mv 2 net ˆ F= r R 11/12/10 Physics 121 18 y 2 (in radians) = (in degrees) 360 = t Uniform motion: 11/12/10 = x t = 0 Physics 121 t 19 ...
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## This note was uploaded on 12/28/2011 for the course PHYSICS 121 taught by Professor Shawhan during the Spring '10 term at Maryland.

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