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s. t. s = ut + 1/2at 2 u and a are positive. v. t. v = u + at u is positive and a is negative. v. s. v 2 = u 2 + 2as u is positive and a is negative. a. t. a-t graph for motion with uniform velocity. Vertical motion under gravity. Motion of a free falling object.
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s t s = ut + 1/2at2u and a are positive
v t v = u + atu is positive and a is negative
v s v2 = u2 + 2asu is positive and a is negative
a t a-t graph for motion with uniform velocity
Slope of v-t graph = acceleration => g = (2.75-0.5)/(3*0.08) = 9.375 ms-2
Q. The experimental value is always smaller than the actual value, why? • When the vibrator strikes the ticker tape, it produces friction which slows down the falling motion. • The falling motion is slowed down by air resistance.
coin feather fall in air fall in vacuum Acceleration due to gravity (g)
gravitational force air resistance fall in air fall in vacuum
Air resistance depends on: • Size of the object • Shape of the object • Its velocity • => parachute
A ball is thrown vertically upwards at an initial velocity of 100 m s-1. • What is the acceleration of the ball along the time of flight?