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3 years ago

13

A ball is thrown horizontally at a speed of 24 m/s from the top of a cliff. if the ball hits the ground 4.0 s later, approximate

ly how high is the cliff?

1 answer:

marishachu [46]3 years ago

6 0

144 m 24 divided by 4 = 6 24 x 6 = 144

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A constant 10.0-N horizontal force is applied to a 20.0-kg cart at rest on a level floor. If friction is negligible, what is the

Otrada [13]

Answer:

2.83 m/s

Explanation:

Given:

Mass of the cart (m) = 20.0 kg

Initial velocity of the cart (u) = 0 m/s

Final velocity (v) = ? m/s

Displacement of the cart (S) = 8.0 m

Horizontal force acting on the cart (F) = 10.0 N

Surface is frictionless. So, only horizontal force is the force acting on the cart.

Now, as per work-energy theorem, the work done by the net force acting on a body is equal to the change in the kinetic energy of the body.

Here, the work done by the horizontal force is given as:

$W_{net}=FS=(10\ N)(8.0\ m)=80\ Nm$

The change in kinetic energy is given as:

$\Delta K=\frac{1}{2}m(v^2-u^2)\\\\\Delta K=\frac{1}{2}(20.0\ kg)(v^2-0)\\\\\Delta K=10v^2$

Now, from work-energy theorem:

$\Delta K=W_{net}\\\\10v^2=80\\\\v^2=\frac{80}{10}\\\\v=\sqrt{8}=2.83\ m/s$

Therefore, the speed of the cart when it has been pushed 8.0 m is 2.83 m/s.

5 0

3 years ago

You observe a distant galaxy. You find that a spectral line of hydrogen that is shifted from its normal location in the visible

dimulka [17.4K]

Answer:

The galaxy is moving away from us

Explanation:

Galaxy refers to a system of millions or billions of stars accompanied by gas and dust such that they are held together as a result of gravitational attraction.

When we observe a distant galaxy, we find that a spectral line of hydrogen that is shifted from its normal location in the visible part of the spectrum into the infrared part of the spectrum.

It means that the galaxy is moving away from us.

6 0

3 years ago

Sound Waves can be used to measure ocean depth. This done by sending a sound wave to the floor of the ocean and recording the ti

vazorg [7]

When the sound wave returns to the machine, you can measure
how long it took to return.

(You may notice that it's working just like RADAR, which does the
same thing with radio waves instead of sound waves.)

Even if you know how long the sound took to get to the bottom and
return to the top, you can't DO anything with this information if you
don't know the SPEED of the sound through the water. Not only
the inventory of this machine, but anyone who uses it, has to know
the speed of the sound through water in order to use the round-trip
time to calculate the depth.

3 0

3 years ago

The sun's energy is stored in fossil fuels. true or false.

Scilla [17]

Yes,suns original energy are still stored at the bonds of fossils in which they taken long,long time ago and these fossils powered now industries,fuel for vehicles.In those chemical bonds holds much energy packed together for centuries.

8 0

3 years ago

sledge (including load) weighs 5000 N. It is pulled on level snow by a dog team exerting ahorizontal force on it. The coeﬃcient

lara31 [8.8K]

Answer:

2.5 x 10^{5} J

Explanation:

weight = 5,000 N

coefficient of friction = 0.05

distance = 1000 m

how much work is done by the dogs pulling the sledge

work done = force x coefficient of friction x distance

work done = 5000 x 0.05 x 1000 = 2.5 x 10^{5} J

6 0

3 years ago