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sveta [45]
3 years ago
9

A construction crane lowers a beam into place at constant speed. Consider the work Wg done by gravity on the beam and the work W

T done by the tension in the cable on the beam. Which is true?
A) Wi is positive and Wr is positive.
B) We is positive and W'r is negative.
C) Wg is negative and W'r is negative.
D) Wi and W'r are both zero.
E) None of the above
Physics
1 answer:
aalyn [17]3 years ago
5 0

Answer:

Wg is positive and WT negative.

(Letters in options are all wrongly written).

Explanation:

Remember that the work of a force is the internal product between the force and the displacement W=F.d.

Since the displacement is downwards like the weight, the work done by gravity is positive, while the work done by the tension is negative since it points upwards.

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A jetliner flies east 2000 miles from San Francisco to Chicago. It has an average air speed of 600 mph relative to the air. What
mariarad [96]

Answer:

750 mph, east

Explanation:

The jetliner is going from San Francisco to Chicago... so it's moving from West to East, at 600 mph, relative to the air.

The wind is also moving from West to East, at 150 mph.

Since both are going in the same direction, we combine the speeds by adding them to each other.  If they were in opposite direction, we would subtract them.

So, 600 mph for the plane + 150 mph for the wind = 750 mph, going EAST.

7 0
3 years ago
Momentum
puteri [66]

Answer:

get egg and try to make in not crack when it falls by exerting the momentum of the fall into something other than the egg ex. make a box full of bubble wrap and put your egg in it

Explanation:

8 0
3 years ago
Which would most likely cause molten rock material to become glassy igneous rock?
Ainat [17]
The cooling on earth's surface (extrusive)  makes a molten rock to become glassy. The lava cools so fast that crystals don't have time to form, which makes it glassy. Hope this helps!
6 0
3 years ago
Explain how if a solid, liquid, and gas are put into individual containers how they fill the container.
Sav [38]

Answer:

serial in which container is filled

Solid -base of container

Liquid- above solid

Gas- above liquid

Explanation:

If any mixture of  matter in different state (that solid , liquid or gas )are kept in any container, then substance with higher density will be settled at lowest surface first and similarly the substance with lowest density will be at upper part of container.

In the given container we have to keep solid, liquid and gas

  • sold has the highest density,
  • gas the lowest density and
  • liquid has the density higher than gas but less than solid.

based on this

solid will be at surface of container

above sold will be liquid

above liquid will be presence of Gas

serial in which container is filled

Solid -base of container

Liquid- above solid

Gas- above liquid

8 0
4 years ago
Water is flowing in a pipe with a varying cross-sectional area, and at all points the water completely fills the pipe. At point
Salsk061 [2.6K]

Answer:

The fluids speed at a) 0.105\,m^{2}  and b) 0.047\,m^{2} are 2.33\,\frac{m}{s^{2}}  and 5.21\,\frac{m}{s^{2}} respectively

c) Th volume of water the pipe discharges is: 882\,m^{3}  

Explanation:

To solve a) and b) we should use flow continuity for ideal fluids:

\Delta Q=0(1)

With Q the flux of water, but Q is Av using this on (1) we have:

A_{2}v_{2}-A_{1}v_{1}=0 (2)

With A the cross sectional areas and v the velocities of the fluid.

a) Here, we use that point 2 has a cross-sectional area equal to A_{2}=0.105\,m^{2}, so now we can solve (2) for v_{2}:

v_{2}=\frac{A_{1}v_{1}}{A_{2}}=\frac{(0.070)(3.5)}{0.105}\approx2.33\,\frac{m}{s^{2}}

b) Here we use point 2 as A_{2}=0.047\,m^{2}:

v_{2}=\frac{A_{1}v_{1}}{A_{2}}=\frac{(0.070)(3.5)}{0.047}\approx5.21\,\frac{m}{s^{2}}

c) Here we need to know that in this case the flow is the volume of water that passes a cross-sectional area per unit time, this is Q=\frac{V}{t}, so we can write:

A_{1}v_{1}=\frac{V}{t}, solving for V:

V=A_{1}v_{1}t=(0.070m^{2})(3.5\frac{m}{s})(3600s)=882\,m^{3}

3 0
4 years ago
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