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3 years ago

Work is done when a person at rest holds a package vertically a. true b. false

Physics

1 answer:

Ksivusya [100]3 years ago

6 0

Answer:

False

Explanation:

Work= F*D and since the box isn't moving moved resulting in its displacement equalling 0, the work done on the package is 0.

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What is a substance

Korolek [52]

Explanation:

A particular kind of matter with uniform properties..

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3 years ago

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The speed of an aircraft is sometimes expressed as a mach number: mach 1 means that the speed is equal to the speed of sound. if

mars1129 [50]

The speed of sound needs to be given, in the proper form. This will allow for the proper conversion (namely, a multiplication by the Mach rate) to find the actual speed that the aircraft is traveling, compared to how fast sound travels.

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3 years ago

Gravity is defined as: Select one: a. an apple falling from a tree toward the ground. b. ability to accomplish a job with the le

Scorpion4ik [409]

Answer:

c. natural force or pull toward the earth

Explanation:

Gravity of the earth is the force of attraction that it naturally possesses to attract any mass.

An apple falls on the earth due to this force of gravity.

The force of gravity near to the surface of the earth is given as:

$F=m.g$

where:

m= mass of the body

g= acceleration due to gravity

The variation of the gravitational force with height is given as:

$F'=m.g'$

where:

$g'=g\times (1+\frac{h}{R} )^{-2}$

where

R = radius of the earth $\approx64000\ km$

4 0

3 years ago

3. A 2kg wooden block whose initial speed is 3 m/s slides on a smooth floor for 2 meters before it comes to a

serious [3.7K]

Answer:

Calculating Coefficient of friction is 0.229.

Force is 4.5 N that keep the block moving at a constant speed.

Explanation:

We know that speed expression is as $\mathrm{V}^{2}=\mathrm{V}_{\mathrm{i}}^{2}+2 . \mathrm{a} . \Delta \mathrm{s}$ .

Where, ${V}_{i}$ is initial speed, V is final speed, ∆s displacement and a acceleration.

Given that,

${V}_{i}$ =3 m/s, V = 0 m/s, and ∆s = 2 m

Substitute the values in the above formula,

$0=3^{2}-2 \times 2 \times a$

0 = 9 - 4a

4a = 9

$a=2.25 \mathrm{m} / \mathrm{s}^{2}$

$a=2.25 \mathrm{m} / \mathrm{s}^{2}$ is the acceleration.

Calculating Coefficient of friction:

$\mathrm{F}=\mathrm{m} \times \mathrm{a}$

$\mathrm{F}=\mu \times \mathrm{m} \times \mathrm{g}$

Compare the above equation

$\mu \times m \times g=m \times a$

Cancel "m" common term in both L.H.S and R.H.S

$\text { Equation becomes, } \mu \times g=a$

$\text { Coefficient of friction } \mu=\frac{a}{g}$

$\mathrm{g} \text { on earth surface }=9.8 \mathrm{m} / \mathrm{s}^{2}$

$\mu=\frac{2.25}{9.8}$

$\mu=0.229$

Hence coefficient of friction is 0.229.

calculating force:

$\text { We know that } \mathrm{F}=\mathrm{m} \times \mathrm{a}$

$\mathrm{F}=2 \times 2.25 \quad(\mathrm{m}=2 \mathrm{kg} \text { given })$

F = 4.5 N

Therefore, the force would be 4.5 N to keep the block moving at a constant speed across the floor.

7 0

3 years ago

You have family members and the relationship you observed in childhood affects the quality of your current relationships?

Ghella [55]

Answer:

Yes, the relationships you observe in childhood affects the quality of your current relationships.

Explanation:

The saying, "Children see, children do," is evidently true. A child's lifestyle and future relationships are greatly affected by the kind of relationships you allow him to see. Thus, it is very important that parents become role models for their kids.

For example, when your parents handle stress by shouting at each other, then most likely you'd also handle stress the same way in the future. So, it is essential that the role models will show the child how to handle stress positively. The experiences that children have at a young age affects their adult life. It influences them and shapes them into who they will become.

If people at home show positive relationships with each other and also supports a child regarding his education, then the child will most likely set positive relationships with his peers and achieve higher degree standards.

Thus, this explains the answer.

4 0

3 years ago