having to push a rough and heavy box across the floor to move it
Explanation:
Friction is not a useful force because we have to exert even more force to push a body that is rough and heavy across the floor to move it.
- Frictional force is a force that opposes the motion of a body.
- It costs more and uses more energy to push a rough and heavy box on surface because of friction.
- This wastes energy in systems that deals with pushing.
Friction is useful in that:
- the heat energy produced when two surfaces rub together is very useful.
- the friction between your feet and the floor keeping you from slipping and makes walking possible.
- the tread on tires helping the moving vehicle slow down and stop when necessary.
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Answer:
Option (d)
Explanation:
The electrons in a conductor moves with the drift velocity when the electric current is flowing through the conductor.
The drift velocity is due to the applied electric field across the conductor.
When galaxies move farther away the wavelength of the light is longer causing the galaxy to shift red but if it moves closer, the wavelength of the light gets smaller causing the galaxy to blue shift. The reason that the wavelength increases or decrease is due to the doppler effect.
We know that
• The sphere diameter is 8.55 cm.
,
• The temperature change is from 30 C to 155 C.
First, we have to find the radius of the sphere. The radius is the half diameter.
Now we have to find the volume of the sphere using the following formula.
Where r = 4.275 cm.
Then, we use the following formula
Where the initial volume is 327.26 cubic cm, B is a constant about thermal expansion for aluminum, and we have to find the final volume to then calculate the percentage change.
This means that the volume change is 3.07 cubic centimeters.
At last, we have to divide the volume change by the initial volume, and then we have to multiply it by 100% to express it as a percentage.
<h2>Therefore, the percentage change is 0.938%.</h2>
Answer:
Asking a question
Research existing sources
Define an hypothesis
Design and conduct a study
Draw conclusion
Report result.
Explanation:
Scientific study simply means establishing the existence or proving the veracity of an hypothesis, hence making it a fact. A scientific study follows an orders set of procedure;
Asking a question is the first step as this is what prompts the research, question usually stems after making an observation.
The a observation made and question asked will lead to making research on the observed phenomenon, this is to check if such question has been asked in the past and maybe any scientific study as been carried out in the past.
To make research further, an hypothesis is defined in a bid to find more evidence to support one's observation through experiment.
Study design and implementation is next as the type of study to be embarked upon will determine which type of design preparation and study pattern to deploy.
Conclusion a d report of observations made are the last part of a scientific study which is key as all outcomes of the study should be adequately detailed in an understandable format while also ensuring reproducibility.
