Newton's first law of motion is sometimes called the law of ________

A man of mass 50kg ascends a flight of stairs 5m high in 5 seconds. If acceleration due to gravity is 10ms-2, the power expended

Setler79 [48]

The power expended is 500 W

Explanation:

First of all, we start by calculating the work done by the man in order to ascend: this is equal to the gravitational potential energy gained by the man, which is

$W=mg\Delta h$

where

m = 50 kg is the mass of the man

$g=10 m/s^2$ is the acceleration of gravity

$\Delta h = 5 m$ is the change in height

Substituting,

$W=(50)(10)(5)=2500 J$

Now we can calculate the power expended, which is given by

$P=\frac{W}{t}$

where

W = 2500 J is the work done

t = 5 s is the time elapsed

Substituting, we find

$P=\frac{2500}{5}=500 W$

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7 0

3 years ago

A spring has a spring constant of 55 N/m. How much energy is stored in the spring when it is compressed 0.3 m past it's natural

mixer [17]

E = 0.5kx² = 0.5 * 55 * 0.3² = 2.475

6 0

3 years ago

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Use what you know about mass and how you use it to calculate force in the following situation. If each washer has a mass of 4. 9

mina [271]

Considering the change of units and the definition of weight, the mass of two washers would be 0.0098 kg and if 4 washers are attached to the string, then the applied force on the car will be 0.196 N.

Mass of two washers

If each washer has a mass of 4.9 g, then the mass of two washers will be calculated simply by multiplying the mass of 1 washer by the amount you have of them, in this case 2:

4.9 g×2= 9.8 g

Being 1 kg = 1000 g, you apply the following rule of three to make the change of units: if 1000 g equals 1 kg, 9.8 g equals how many kilograms?

$mass=\frac{9.8 gramsx1 kg}{1000g}$

Solving:

mass= 0.0098 kg

Finally, the mass of two washers would be 0.0098 kg.

Applied force

On the other side, mass is the amount of matter that a body contains and weight is the action exerted by the force of gravity on the body.

The mass of an object will always be the same, no matter where it is located. Instead, the weight of the object will vary according to the force of gravity acting on it.

Weight is calculated as the product of the object's mass and the value of the gravitational acceleration:

W= m×g

In this case, you know:

m= 4.9 g×4= 19.6 g= 0.0196 kg → the mass of 4 washers in kilograms
g= 10 m/s²

Replacing:

W= 0.0196 kg× 10 m/s²

Solving:

W= 0.196 N

Finally, if 4 washers are attached to the string, then the applied force on the car will be 0.196 N.

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7 0

3 years ago

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The period of a pendulum is measured 16 times. The average value of the period over these 16 trials is calculated to be 1.50 sec

marin [14]

Answer:

The additional trials needed is 48 trials

Explanation:

Given;

initial number of trials, n = 16 trials

the standard deviation, σ = 0.24 s

initial standard error, ε = 0.06 s

The standard error is given by;

$\epsilon = \frac{\sigma}{\sqrt{n} }$

To reduce the standard error to 0.03 s, let the additional number of trials = x

$0.03= \frac{0.24}{\sqrt{n+x} } \\\\0.03= \frac{0.24}{\sqrt{16+x} }\\\\0.03\sqrt{16+x} = 0.24\\\\\sqrt{16+x} = \frac{0.24}{0.03} \\\\\sqrt{16+x} = 8\\\\16+x = 8^2\\\\16+x = 64\\\\x = 64 -16\\\\x = 48 \ trials$

Therefore, the additional trials needed is 48 trials.

6 0

3 years ago

Identify the following physical quantities as scalars or vectors.

34kurt

Position displacement velocity acceleration are vectors and the rest are scalars

6 0

4 years ago

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Newton's first law of motion is sometimes called the law of _________.