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Home » A ball is thrown from a roof top at an angle of 45o above the horizontal. It hits the ground a few seconds later. At what point during its motion, does the ball have a) greatest speed b) smallest speed c) greatest acceleration? Explain
A ball is thrown from a roof top at an angle of 45o above the horizontal. It hits the ground a few seconds later. At what point during its motion, does the ball have a) greatest speed b) smallest speed c) greatest acceleration? Explain
CBSE | Class 11 | Motion in a Plane | NCERT | Physics
A ball is thrown from a roof top at an angle of 45o above the horizontal. It hits the ground a few seconds later. At what point during its motion, does the ball have a) greatest speed b) smallest speed c) greatest acceleration? Explain

Answer:

a) Assume the ball is thrown 45^o from O. The ball’s height increases from O to A, lowering its KE. The speed increases as the height lowers from A to B, until it reaches the initial speed when the ball was at O. O and B are on the same horizontal line. From B to C, speed increases as height decreases.

So v_y max at C and v_x = u/2.

B) Point A has the slowest speed since the height is highest and vy = 0 because the horizontal speed is constant (ie; u/2).

c) The greatest acceleration is attributable to gravity, as only gravity acts downward on the ball.

i

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