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3 years ago

1. All of the following show friction as a useful force, except _____.

2 answers:

7 0

1. Having to push a rough and heavy box across the floor to move it.
2. The coefficient of sliding friction will decrease.
3. Greater than the friction involved in rolling an object.
4. Drag.
5. Sliding (kinetic) friction. Sliding friction is also known as kinetic friction - force that is needed to keep a surface sliding along another surface.

ozzi3 years ago

4 0

1. having to push a rough and heavy box across the floor to move it

In this case, friction is not a useful force: in fact, our aim is to push the box across the floor and move it, while the direction of the friction is against the motion of the box, so this means that we have to do more work in order to win the friction and move the box.

2. The coefficient of sliding friction will stay the same.

In fact, the coefficient of sliding friction does not depend on the mass or the size of the object, but it depends only on the two materials which are in contact between each other (so, the material of the object and the material of the floor/surface).

3. the friction involved in sliding an object is greater than the friction involved in rolling an object

This can be explained by thinking that when sliding an object, the area of contact between the object and surface is generally larger than the area of contact when rolling an object (ideally, there is only one point of contact between the object and the surface when rolling an object), so friction has a greater effect.

4. drag

Drag is the frictional force exerted by a fluid (liquid or gas) on a solid object moving through the fluid. In particular, it is due to the contact between the surface of the object and the molecules of fluid: part of the energy of the object is transmitted to the molecules of the fluid, and the object decelerates.

5. kinetic friction

Kinetic friction is the force of reistance that occurs when an object is being pulled over a surface, and its formula is given by

$F_f = \mu m g$

where $\mu$ is the coefficient of friction, m is the mass of the object and g is the gravitational acceleration.

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3 years ago

How can a global dependence on fossil fuels have associated social costs?

stiv31 [10]

Answer:

Global dependence on fossil fuels has associated social costs.

Explanation:

Increased dependence on fossil fuels reduces their availability. When the demand is high and the availability is low, the price rises. Not every nation would then be able to afford buying fossil fuels at such high costs.

Developing and underdeveloped countries would then be left behind and only the wealthy nations would be able to afford fossil fuel purchase. This would be the immediate impact of global dependence on fossil fuels.

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3 years ago

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How long would it take for a ball dropped from the top of a 576-foot building to hit the ground? round your answer to two decima

LUCKY_DIMON [66]

If a ball is if a ball is dropped from a 576ft building it would take about 8 seconds for it to hit the ground.

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3 years ago

A +1.0 nC charge is at x = 0 cm, a -1.0 nC charge is at x = 1.0 cm and a 4.0 nC at x= 2 cm. What is the electric potential energ

lesantik [10]

Answer:

- 2.7 x 10^-6 J

Explanation:

q1 = 1 nC at x = 0 cm

q2 = - 1 nC at x = 1 cm

q3 = 4 nC at x = 2 cm

The formula for the potential energy between the two charges is given by

$U=\frac{Kq_{1}q_{2}}{r}$

where r be the distance between the two charges

By use of superposition principle, the total energy of the system is given by

$U = U_{1,2}+U_{2,3}+U_{3,1}$

$U=\frac{Kq_{1}q_{2}}{0.01}+\frac{Kq_{2}q_{3}}{0.01}+\frac{Kq_{3}q_{1}}{0.02}$

$U=-\frac{9\times10^{9}\times 1\times10^{-9}\times 1\times10^{-9}}}{0.01}-\frac{9\times10^{9}\times 1\times10^{-9}\times 4\times10^{-9}}}{0.01}+-\frac{9\times10^{9}\times 1\times10^{-9}\times 4\times10^{-9}}}{0.02}$

U = - 2.7 x 10^-6 J

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3 years ago

1. Is there a relationship between the volume of water displaced and the total volume of the block that has anything to do with

strojnjashka [21]

Answer:

The volume of the block is equal to the volume of water displaced by the block.

Explanation:

Volume refers to the amount of space occupied by a given object (in this case the block). When an object such as the block is immersed in water, it displaces its own volume of water. This volume of water displaced is equal to the volume of the block. Hence we can write;

Final Volume of water - Initial Volume of water= Water Displaced = Volume of the block

Recall that the density of a body is given by;

Density= mass/volume

If we obtain the volume of the block by measuring the volume of water displaced by the block, then we weigh the block using a weighing balance, we can obtain the density of the block easily from the relationship shown above.

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3 years ago