A ball is projected horizontally with a velocity of 30 m/s from the top of a high tower. Air resistance may be neglected. After what time will its velocity be in the direction 45 degrees to the horizontal?
Answer (2)
Its velocity will point down 45 degrees when its vertical speed has grown to 30 m/s to match its horizontal speed.
Gravity is increasing the downward speed of the ball by 9.8m/s every second.
So its downward speed will be 30 m/s after (30) / (9.8) = 3.06 seconds
The ball's velocity will be at a 45-degree angle after approximately 3.06 seconds. This is when the vertical speed matches the constant horizontal speed of 30 m/s. The vertical speed increases due to gravity at a rate of 9.8 m/s².
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