Page 77 - eEISBN FINALIZE
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Objects falling in a vacuum
accelerate at the same rate
regardless of their mass or size.
• An object moving vertically in a straight line can be modelled as a particle with a constant
-2
downward acceleration of g= 9.8 ms
• When solving problems about vertical motion you can choose the positive direction to be
either upwards or downwards. Acceleration due to gravity is always downwards, so if the
-2
positive direction is upwards then a = -9.8 ms
• The total time that an object is in motion from the time it is projected (thrown) upwards to
the time it hits the ground is called the time of flight. The initial speed is sometimes called
he speed of projection.
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