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3 years ago

8

When a cup is placed on a table, which force prevents the cup from falling to the ground? A. gravitational force B. normal force

C. resistance force D. tension force

2 answers:

stealth61 [152]3 years ago

6 0

its B... normal force

meriva3 years ago

6 0

Answer:

here normal force will balance the weight of cup which will prevent it from falling

B. normal force

Explanation:

When cup is placed on the table then there will be two forces on the cup

1). Normal force due to table which will be perpendicular to the table and acting upwards

2). gravitational force or weight of the cup which acts perpendicular downwards

now since the cup is at rest so net force on the cup must be balanced

so we can say

$F_g - F_n = 0$

so here we will have

$mg - F_n = 0$

so here normal force will balance the weight of cup which will prevent it from falling

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Classify each process according to whether it does or does not produce a new substance.

AlexFokin [52]

The processes under chemical change are: cooking an egg, fireworks exploding, and rusting of a metal tool.

The processes under physical change are: melting ice, evaporating puddle of water, and dissolving of salt in water.

Given:

The following process:

cooking an egg
melting ice
fireworks exploding
evaporating puddle of water
rusting of a metal tool
Dissolving of salt in water

To find:

The classify the processes in whether it does or does not produce a new substance.

Solution:

Chemical change is the change when a new substance is formed due to a change in the chemical composition of the substance.
Physical change is the change in which no change in chemical composition takes place and the identity of the substance remains the same.

Cooking an egg

Chemical change, due to change in atomic arrangement egg get solidified on cooking, a new substance is formed.

Melting ice

Physical change, change in the state of matter is taking from solid to liquid, no new substance is formed.

Firework exploding

Chemical change. formation of carbon dioxide gas and sound energy, anew substance formed

Evaporating puddle of water

Physical change, change in the state of matter is taking from liquid to gas, no new substance is formed.

Rusting of metal tool

Chemical change, formation of oxides on the surface of the metal tool due to reaction between air and metal, a new substance is formed.

Dissolving of salt in water

Physical change, ions of salt in the solid state are changing into aqueous ions with no formation of new substance, no new substance is formed.

The processes under chemical change are: cooking an egg, fireworks exploding, and rusting of a metal tool.

The processes under physical change are: melting ice, evaporating puddle of water, and dissolving of salt in water.

Learn more about physical change and chemical change here:

brainly.com/question/864557?referrer=searchResults

brainly.com/question/13316655?referrer=searchResults

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3 years ago

# A cheetah can start from rest and attain the velocity 72km/h in 2 seconds. Calculate the acceleration of cheetah

yan [13]

Answer:

<h2> $10 \:$ m/s ^2</h2><h2 />

Explanation:

Solution,

When a certain object comes in motion from rest, in the case, initial velocity = 0 m/s

Initial velocity ( u ) = 0 m/s

Final velocity ( v ) = 72 km/h ( Given)

We have to convert 72 km /h in m/s

$72 \: km \: per \: hour$

$= 72 \times \frac{1000}{60 \times 60}$

$= 20$ m/s

Final velocity ( v ) = 20 m/s

Time taken ( t ) = 2 seconds

Acceleration (a) = ?

Now,

we have,

$a = \frac{v - u}{t}$

$a = \frac{20 - 0}{2}$

$a = \frac{20}{2}$

$a = 10$ m/s ^2

Hope this helps...

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7 0

3 years ago

An isotope is a version of the same element that differs in the composition of the A) atom. B) nucleus. C) particle. Eliminate D

crimeas [40]

The correct answer is B because isotopes have different numbers of neutrons, and neutrons are located in the nucleus

Hope this helps

5 0

3 years ago

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Starting from zero, the electric current takes 2 seconds to reach half its maximum possible value in an RL circuit with a resist

Leno4ka [110]

Answer:

time=4s

Explanation:

we know that in a RL circuit with a resistance R, an inductance L and a battery of emf E, the current (i) will vary in following fashion

$i(t)=\frac{E}{R}(1-e^\frac{-t}{\frac{L}{R}})$ , where $i$ max= $\frac{E}{R}$

Given that, at i(2)= $\frac{imax}{2} =\frac{E}{2R}$

⇒ $\frac{E}{2R}=\frac{E}{R}(1-e^\frac{-2}{\frac{L}{R}})$

⇒ $\frac{1}{2}=1-e^\frac{-2}{\frac{L}{R}}$

⇒ $\frac{1}{2}=e^\frac{-2}{\frac{L}{R}}$

Applying logarithm on both sides,

⇒ $log(\frac{1}{2})=\frac{-2}{\frac{L}{R}}$

⇒ $log(2)=\frac{2}{\frac{L}{R}}$

⇒ $\frac{L}{R}=\frac{2}{log2}$

Now substitute $i(t)=\frac{3}{4}imax=\frac{3E}{4R}$

⇒ $\frac{3E}{4R}=\frac{E}{R}(1-e^\frac{-t}{\frac{L}{R}})$

⇒ $\frac{3}{4}=1-e^\frac{-t}{\frac{L}{R}}$

⇒ $\frac{1}{4}=e^\frac{-t}{\frac{L}{R}}$

Applying logarithm on both sides,

⇒ $log(\frac{1}{4})=\frac{-t}{\frac{L}{R}}$

⇒ $log(4)=\frac{t}{\frac{L}{R}}$

⇒ $t=log4\frac{L}{R}$

now subs. $\frac{L}{R}=\frac{2}{log2}$

⇒ $t=log4\frac{2}{log2}$

also $log4=log2^{2}=2log2$

⇒ $t=2log2\frac{2}{log2}$

⇒ $t=4$

5 0

3 years ago

Which describes how light travels?

trasher [3.6K]

Answer:

the Answer Would be D

Explanation:

From what I know light travels 300,000 km/second , travels at fast speeds and travels in a straight line

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3 years ago

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