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3 years ago

An object is 45 m above the ground when it is dropped. How fast is the object going just before it hits the ground?

1 answer:

3 0

This is a kinematics question.
$v^{2} = v_{0} ^{2} + 2g(y - y_{0}) \\ 
v^{2} = 0 + 2(-9.8)(0 - 45) \\ 
v^{2} = 882 \\ v = \sqrt{882} = 29.7 m/s$

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A ball filled with an unknown material starts from rest at the top of a 2 m high incline that makes a 28o with respect to the ho

Lady_Fox [76]

Answer:

Searching in google I found the total mass and the radius of the ball (m = 1.5 kg and r = 10 cm) which are needed to solve the problem!

The ball rotates 6.78 revolutions.

Explanation:

Searching in google I found the total mass and the radius of the ball (m = 1.5 kg and r = 10 cm) which are needed to solve the problem!

At the bottom the ball has the following angular speed:

$\omega_{f} = \frac{v_{f}}{r} = \frac{4.9 m/s}{0.10 m} = 49 rad/s$

Now, we need to find the distance traveled by the ball (L) by using θ=28° and h(height) = 2 m:

$sin(\theta) = \frac{h}{L} \rightarrow L = \frac{h}{sin(\theta)} = \frac{2 m}{sin(28)} = 4.26 m$

To find the revolutions we need the time, which can be found using the following equation:

$v_{f} = v_{0} + at$

$t = \frac{v_{f} - v_{0}}{a}$ (1)

So first, we need to find the acceleration:

$v_{f}^{2} = v_{0}^{2} + 2aL \rightarrow a = \frac{v_{f}^{2} - v_{0}^{2}}{2L}$ (2)

By entering equation (2) into (1) we have:

$t = \frac{v_{f} - v_{0}}{\frac{v_{f}^{2} - v_{0}^{2}}{2L}}$

Since it starts from rest (v₀ = 0):

$t = \frac{2L}{v_{f}} = \frac{2*4.26 m}{4.9 m/s} = 1.74 s$

Finally, we can find the revolutions:

$\theta_{f} = \frac{1}{2} \omega_{f}*t = \frac{1}{2}*49 rad/s*1.74 s = 42.63 rad*\frac{1 rev}{2\pi rad} = 6.78 rev$

Therefore, the ball rotates 6.78 revolutions.

I hope it helps you!

3 0

3 years ago

Please help!! I will give brainliest!

grandymaker [24]

Answer:

Depends.

Explanation:

Whether the object is going left or right, the speed will stay the same until friction eventually stops it. However, if, for example, we're talking about an object going straight before veering right, then yes, speed does matter. An object will normally have to speed up or slow down momentarily when changing direction to keep itself sustained on the ground.

So, honestly? It really depends on what we're talking about!

Hope this helped!

Source(s) used: None.

7 0

3 years ago

What is refraction?

Damm [24]

B- light bends as it passes through an object ( a would be reflect)

4 0

3 years ago

Which of the following indicates a heat transfer?

lesya [120]

Answer:

TEMPERATURE CHANGES

Explanation:

WELL ITS BASIC. WHEN TEMPERATURE CHANGES. IT MEANS THAT HEAT IS BEING TRANSFERRED AS I HEARD THAT COLD CANNOT BE TRANSFERRED

3 0

3 years ago

A stunt woman of mass m falls into a net during the filming of an action movie. Assume she experiences upward acceleration magni

Rashid [163]

Answer:

M= F^n / a+g

Explanation:

This shows correctly Newton’s second law, where sum of forces is divided by mass is equal to acceleration. Also mass can’t be negative so F^n is positive.

8 0

3 years ago

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