Physics, 20.01.2020 20:31 cchsemily4651

Calculate the height (in m) of a cliff if it takes 2.47 s for a rock to hit the ground when it is thrown straight up from the cliff with an initial velocity of 8.17 m/s. (enter a number.)

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Answer from: tantoine2704

9.68 m

Explanation:

When a rock is thrown upward from the cliff, it travels upward until it stops midair, then it travel downward to the cliff throwing point, then down to the ground.

Let g = 9.81m/s2. We can calculate the time it takes for the rock to travel until it gets to maximum height, aka speed = 0 using the following equation of motion

v = v_0 + gt

where v0 = 8.17 m/s is the initial upward speed, v = 0m/s is the speed at maximum height

0 = 8.17 - 9.81t

9.81t = 8.17

t = 8.17/9.81 = 0.833 s

According to law of energy conservation, rock would have the same kinetic energy when it fall back to it's throwing point. This means the speed when it travels back to it throwing point would be the same as the launch speed, 8.17m/s, but downward.

It would take the same amount of time t = 0.833s for the rock to gain back that much speed.

So the total time it takes for the rock to travel upward and back to its throwing point is t = 0.833 + 0.833 = 1.665 s

As the total time it takes to hit the ground is 2.47s, the rock would need an additional of 2.47 - 1.665 = 0.8s to travel from the throwing point downward to the ground at initial speed of 8.17m/s and a constant acceleration g = 9.81m/s2

The total distance covered, or height of the cliff would then be

s = vt + gt^2/2 = 8.17*0.8 + 9.81*0.8^2/2 = 9.68 m

Answer from: Quest

The magnets are probably damaged or there not strong enough to attached to the refrigerator

Answer from: Quest

You need to be more specific. i really don't know what a "motion map" is.you can draw a graph of an object's position, distance, displacement, speed,velocity, or acceleration versus time, or you can draw a graph of the object's x-position versus its y-position and not give any information about time at all.if the graph presents position or displacement against time, then constant velocity is a straight line . . i.e. a line that has constant slope.if the graph shows speed against time, then constant velocityis a horizontal piece of line.if the graph shows acceleration against time, then constant velocity is a piece of line that lies on the x-axis . . it's value is zero.

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Calculate the height (in m) of a cliff if it takes 2.47 s for a rock to hit the ground when it is th...

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