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secondary 3 | A Maths
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secondary 3 chevron_right A Maths chevron_right Singapore

need help with part b, pls explain too :)

Date Posted: 3 years ago
Views: 185
Eric Nicholas K
Eric Nicholas K
3 years ago
Part b is actually simply

Speed of car
= Distance / Time
= Length AB / (3/3600) h

Since 1 second is 1/3600 of an hour.

The three seconds it takes the laser gun to detect the position change from A to B is also the same three seconds taken for the car to move from A to B.
Eric Nicholas K
Eric Nicholas K
3 years ago
Part a simply uses the cosine rule, going

AB
= sqrt [120^2 + 160^2 - 2 (120) (160) cos 26]
= 74.0696201
~ 74.1 m

Average speed of car, in km/h
= Distance AB (in km) / Time (in hours)
= (74.0696201 / 1000) km / (3/3600) h
= 88.88354412 km/h
~ 88.9 km/h
LockB
LockB
3 years ago
thx :)

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Tham KY
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