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motikmotik
3 years ago
8

Classify each of the following as a physical change or a chemical change. a) grinding glass: b) rusting of iron: c) burning a ca

ndle: d) sanding wood:
Physics
1 answer:
cluponka [151]3 years ago
5 0

Answer:

<em>Physical change: </em>(a) grinding of glass, (c) burning of candle, (d) sanding wood

<em>Chemical change: </em>(b) rusting of iron.

Explanation:

Physical Change: This is the type of change a matter undergoes, it is easily reversible and no new substance is formed.

Chemical Change: Is one which is not easily reversible and a new substance is formed.

From the question above, the following changes can be classified into physical or chemical change

<em>Physical change: </em>(a) grinding of glass, (c) burning of candle, (d) sanding wood

<em>Chemical change: </em>(b) rusting of iron

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An experiment is designed to see if sleep affects the number of vocabulary words subjects can remember. The dependent variable i
Kaylis [27]

The dependent variable is: <em>"number of vocabulary words subjects can remember"</em>

<h3>Which is the dependent variable?</h3>

In an experiment, we basically see how changing one variable affects another variable.

In this case, the experiment is:

<em>" if sleep affects the number of vocabulary words subjects can remember."</em>

Then the hours of sleep would be the independent variable (the one that the scientist can change) and the number of vocabulary words subjects can remember is the dependent variable (that depends on the independent variable).

So the correct answer is:

<em>"number of vocabulary words subjects can remember"</em>

If you want to learn more about variables:

brainly.com/question/15246027

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7 0
2 years ago
Find the magnitude of the sum of two vectors; A is 5 km , and B is 7 , when the angle btween them is 120
Dimas [21]

Answer: 6.24 km

Explanation:

Given

The magnitude of the first vector(say) \left |  a\right |=5\ km

the magnitude of the second vector(say) \left |  b\right |=7\ km

the angle between them is 120^{\circ}

The resultant vector magnitude is given by

\left |  \vec{R}\right |=\sqrt{a^2+b^2+2ab\cos \theta}

\left |  \vec{R}\right |=\sqrt{5^2+7^2+2\times 5\times 7\cdot \cos 120^{\circ}}\\\left |  \vec{R}\right |=\sqrt{74-35}=\sqrt{39}\\\left |  \vec{R}\right |=6.24\ km

4 0
3 years ago
A boat has a mass of 7660 kg. Its engines generate a drive force of 4080 N due west, while the wind exerts a force of 680 N due
makvit [3.9K]

Answer:

0.29 m/s due west.

Explanation:

According to newton's second law,

Net force acting on an object = mass×acceleration

From the question,

F+F₁+F₂ = ma................ Equation 1

Where F = The force generated from the engine, F₁ = Force exerted by the wind, F₂ = Force exerted due to the water, m = mass of the boat, a = acceleration of the boat.

Given: F = 4080 N , F₁ = -680 N(east), F₂ = -1160 N(east). m = 7660 kg

substitute into equation 1

4080-680-1160 = 7660(a)

2240 = 7660a

Therefore,

a = 2440/7660

a = 0.29 m/s due west.

8 0
3 years ago
As objects grow farther apart, what happens to the force of gravity between them?
Papessa [141]
It decreses Decreases
8 0
3 years ago
A 0.03 kg golf ball is hit off the tee at a speed of 34 m/s. The golf club was in contact with the ball for 0.003 s. What is the
Liula [17]

Answer:

The average force on ball by the golf club is 340 N.

Explanation:

Given that,

Mass of the golf ball, m = 0.03 kg

Initial speed of the ball, u = 0

Final speed of the ball, v = 34 m/s

Time of contact, \Delta t=0.003\ s

We need to find the average force on ball by the golf club. We know that the rate of change of momentum is equal to the net external force applied such that :

F=\dfrac{\Delta p}{\Delta t}\\\\F=\dfrac{mv-mu}{\Delta t}\\\\F=\dfrac{mv}{\Delta t}\\\\F=\dfrac{0.03\ kg\times 34\ m/s}{0.003\ s}\\\\F=340\ N

So, the average force on ball by the golf club is 340 N.

4 0
4 years ago
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