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Question 977920: Hi tutors, can u help me answer this? Thanks
A ball starts rolling from the centre of a 3 m x 4 m room in a direction of 45˚ to the walls. It rolls in a straight line except when it bounces off a wall and it does that at an angle of 45˚.
After it has travelled 20 m, how many times has it bounced off a wall?
A. 5
B. 6
C. 7
D. 8
E. 9
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! A ball starts rolling from the centre of a 3 m x 4 m room in a direction of 45 degs to the walls. It rolls in a straight line except when it bounces off a wall and it does that at an angle of 45 degs.
After it has travelled 20 m, how many times has it bounced off a wall?
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It will bounce off the wall that's 4 m long first then the 3 m wall.
Draw it as 2 parallel walls 4 m apart.
Each pair of bounces it travels 4*sqrt(2) meters.
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20/(4sqrt(2)) =~ 3.55 pairs of bounces
--> 7 bounces
A. 5
B. 6
C. 7
D. 8
E. 9
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