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Licemer1 [7]
4 years ago
9

What is the average speed, over the first 4.0 s of its motion, of a pebble released from rest off a bridge?

Physics
1 answer:
galben [10]4 years ago
8 0

<u>Answer: </u>

 Average speed, over the first 4.0 s of its motion, of a pebble released from rest off a bridge = 19.6 m/s

<u>Explanation: </u>

We have equation of motion , s= ut+\frac{1}{2} at^2, s is the displacement, u is the initial velocity, a is the acceleration and t is the time.

In this case the initial velocity of body = 0 m/s, acceleration = 9.8 m/s^2, we need to calculate displacement when t = 4 seconds.

Substituting

S=0*t+\frac{1}{2} *9.8*4^2\\ \\ S=78.4 meter

So a distance of 78.4 meter has been traveled by pebble in 4 seconds.

Average speed = 78.4/4 = 19.6 m/s



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Explain how surface and subsurface events are integral parts of the rock cycle.
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4 years ago
A girl rolls a ball up an incline and allows it to re- turn to her. For the angle and ball involved, the acceleration of the bal
zalisa [80]

Answer:

3.28 m

3.28 s

Explanation:

We can adopt a system of reference with an axis along the incline, the origin being at the position of the girl and the positive X axis going up slope.

Then we know that the ball is subject to a constant acceleration of 0.25*g (2.45 m/s^2) pointing down slope. Since the acceleration is constant we can use the equation for constant acceleration:

X(t) = X0 + V0 * t + 1/2 * a * t^2

X0 = 0

V0 = 4 m/s

a = -2.45 m/s^2 (because the acceleration is down slope)

Then:

X(t) = 4*t - 1.22*t^2

And the equation for speed is:

V(t) = V0 + a * t

V(t) = 4 - 2.45 * t

If we equate this to zero we can find the moment where it stops and begins rolling down, that will be the highest point:

0 = 4 - 2.45 * t

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t = 1.63 s

Replacing that time on the position equation:

X(1.63) = 4 * 1.63 - 1.22 * 1.63^2 = 3.28 m

To find the time it will take to return we equate the position equation to zero:

0 = 4 * t - 1.22 * t^2

Since this is a quadratic equation it will have to answers, one will be the moment the ball was released (t = 0), the other will eb the moment when it returns:

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t1 = 0

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7 0
3 years ago
A 234.0 g piece of lead is heated to 86.0oC and then dropped into a calorimeter containing 611.0 g of water that initally is at
Vaselesa [24]

Answer:24.70 ^{\circ}C

Explanation:

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mass of lead piece m_l=234 gm\approx 0.234 kg

mass of water in calorimeter m_w=611 gm\approx 0.611 kg

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T=\frac{2173.491}{87.97}=24.70^{\circ}C

3 0
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-- The net force on the foot is zero ... 500N from the leg, pointing forward,
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That's how the leg's speed remains constant ... creating a dent in the ball
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