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3 years ago

Which of the following is a physical change?

2 answers:

4 0

A physical change is when the natural state of an object has or will be changed. Out of the following choices, sawing a piece of wood in half will be the physical change.

Credit for the answer explanation: oopsydaisy

NOTE: THIS ANSWER IS NOT MY ANSWER, BUT I HAVE CONFIRMED THAT IT IS CORRECT.

gladu [14]3 years ago

3 0

The answer would be A

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If a plane has an airspeed of 40 m/s and is experiencing a crosswind of 30 m/s, what is its ground speed in m/s?

Anon25 [30]

<h2>Answer:50 $ms^{-1}$ </h2>

Explanation:

Let $v_{a}$ be the airspeed.

Let $v_{w}$ be the cross wind speed.

We know that,ground speed is the vector sum of airspeed and cross wind speed and airspeed is perpendicular to cross wind speed.

If $v_{1}$ and $v_{2}$ are two perpendicular vectors,the resultant vector has the magnitude $\sqrt{|v|_{1}^{2}+|v|_{2}^{2}}$

Given,

$v_{a}=40ms^{-1}\\v_{c}=30ms^{-1}$

So,the ground speed is $\sqrt{40^{2}+30^{2}}=\sqrt{2500}=50ms^{-1}$

6 0

3 years ago

A 65-kg ice skater stands facing a wall with his arms bent and then pushes away from the wall by straightening his arms. At the

Marrrta [24]

Our values can be defined like this,

$m = 65kg$

$v = 3.5m / s$

$d = 0.55m$

The problem can be solved for part A, through the Work Theorem that says the following,

$W = \Delta KE$

Where

KE = Kinetic energy,

Given things like that and replacing we have that the work is given by

W = Fd

and kinetic energy by

$\frac {1} {2} mv ^ 2$

So,

$Fd = \frac {1} {2} m ^ 2$

Clearing F,

$F = \frac {mv ^ 2} {2d}$

Replacing the values

$F = \frac {(65) (3.5)} {2 * 0.55}$

$F = 723.9N$

B) The work done by the wall is zero since there was no displacement of the wall, that is d = 0.

6 0

2 years ago

Please help me I need this for a test

Marysya12 [62]

Answer:

Explanation:

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8 0

3 years ago

Multiple Choice

Digiron [165]

Answer:

What was not required by the Massachusetts Education law of 1642 is;

Children were to be sent to designated schoolmaster for their learning

Explanation:

The Law of 1642 required that parents and master see to it that their children knew the principles of religion and the capital laws of the commonwealth.

The important aspects of the 1642 Law includes;

1) The responsibility for the basic education and literacy of a child are those of the parents and masters of child apprentices

2) Reading and writing competency of all children and servants are a requirement

3) It is the duty of the government, where a parent or master are unable to meet their tutoring responsibility, to see that a child is placed where the basic educational requirement will be met.

The role of a schoolmaster or the setting of a formal school were yet to be formed as at that time.

8 0

3 years ago

Find deacceleration An engineer in a locomotive sees a car stuck on the track at a railroad crossing in front of the train. When

earnstyle [38]

Answer:

The deceleration is $a = -0.7273 \ m/s^2$