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Physics: Post your doubts here!

janasalem

janasalem

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can someone please explain this ?

A student makes measurements from which she calculates the speed of sound as 327.66 m s–1.
She estimates that her result is accurate to ±3 %.
Which of the following gives her result expressed to the appropriate number of significant figures?
A 327.7 m s–1
B 328 m s–1
C 330 m s–1
D 300 m s–1
 
A

Awesome12

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princess Anu said:
Q: A man stands on the edge of a cliff and throws a stone vertically upwards at 15m.s^-1. after what time will the stone hit the ground 20m below.
Click to expand...
u = 15 m/s

s = -20 m (The stone goes up, comes down to the height of the person = No displacement. But it goes back down again to the bottom of the cliff, because it is going below its starting point. In A Level physics, we usually deal with such value by assigning them a negative sign)

a = - 9.81 m/s^2 (The stone is moving against gravity)

t = ?


s = ut +1/2at^2

Find the value of t (you will get two values probably, use the non-zero/non-negative one)
 
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