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3 years ago

How much work is done in lifting a 1.4-kg book off the floor to put it on a desk that is 0.7 m high?

Mathematics

1 answer:

nalin [4]3 years ago

3 0

Answer:

Step-by-step explanation:

Work is said to be done when a force applied to an object cause the body to move in a specified direction.

Work-done = Force * Distance

Since Force = mass * acceleration due to gravity

Work-done = mass * acceleration due to gravity * distance

Given mass = 1.4kg, distance = 0.7m and g = 9.8m/s²

Workdone in lifting the book off the floor = 1.4*0.7*9.8

Workdone = 9.604Joules

- Similarly, work done in lifting a 21-lb weight book 6 ft off the ground is expressed using the same formula as above;

Given mass = 21-lb, g = 32ft/s² and distance = 6ft

Workdone = 21 * 32 * 6

Workdone = 4,032 lb-ft²/s²

Hence, work-done in lifting a 21-lb weight book 6 ft off the ground is 4,032 lb-ft²/s²

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The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customer

AlladinOne [14]

Answer:

$4-2.326\frac{1}{\sqrt{100}}=3.767$

$4+2.326\frac{1}{\sqrt{100}}=4.233$

So on this case the 98% confidence interval would be given by (3.767;4.233)

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

$\bar X=4$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma=1$ represent the population standard deviation

n=100 represent the sample size

Solution to the problem

The confidence interval for the mean is given by the following formula:

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

Since the Confidence is 0.98 or 98%, the value of $\alpha=0.02$ and $\alpha/2 =0.01$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.01,0,1)".And we see that $z_{\alpha/2}=2.326$

Now we have everything in order to replace into formula (1):

$4-2.326\frac{1}{\sqrt{100}}=3.767$

$4+2.326\frac{1}{\sqrt{100}}=4.233$

So on this case the 98% confidence interval would be given by (3.767;4.233)

4 0

3 years ago

How to do this problem and the answer

irga5000 [103]

Use a protractor to do the problem, but try finding th answer yourself

4 0

3 years ago

Read 2 more answers

Please help I’m about to fail and this quiz will bring my grade up.

konstantin123 [22]

Answer:

first blank: -1

second blank: -7

third blank: -13

fourth blank: - 19

Step-by-step explanation:

hope this helps and please rate my answer!

5 0

3 years ago

A local health club has a large swimming pool non member must pay a 6$ per day fee to use the pool member of the club pay 1$ but

vazorg [7]

Answer:

50 days

Step-by-step explanation:

Step one:'

given data

Non member must pay a 6$ per day

let number of days be x

cost = 6x

member of the club pay 1$ but must pay a yearly membership fee of 250

cost = 250+x

Step two

equate the two expression to find x

6x=250+x

6x-x= 250

5x=250

divide both sides by 5

x= 250/5

x=50 days

3 0

2 years ago

Last Friday Adam had $22.33. Over the weekend he received some money for cleaning the attic he now has $32 how much money did he

defon

Answer:

9.67

Step-by-step explanation:

32-22.33=9.67

Hope it helps ;)

8 0

3 years ago

Read 2 more answers