Rust, photosynthesis, and heat from fire are all chemical reactions <span>because </span>new substances are formed and the chemical formula is changed. By doing this, bonds are broken and formed in the making of the new substance. Melting ice is physical change the molecules are still water molecules, it just changed physical form.
I think the correct answer is C
A 100kg crate slides along a floor with a starting velocity of 21 m/s. If the force due to friction is 8N, then, it will take 262.5 s for the box to come to rest.
We'll begin by calculating the declaration of the box. This can be obtained as follow:
Force (F) = –8 N (opposition)
Mass (m) = 100 Kg
<h3>Deceleration (a) =? </h3>
<h3>F = ma</h3>
–8 = 100 × a
Divide both side by 1000

<h3>a = –0.08 ms¯²</h3>
Therefore, the deceleration of the box is –0.08 ms¯²
Finally, we shall determine the time taken for the box to come to rest. This can be obtained as follow:
Deceleration (a) = –0.08 ms¯²
Initial velocity (u) = 21 ms¯¹
Final velocity (v) = 0 ms¯¹
<h3>Time (t) =.? </h3>
<h3>v = u + at</h3>
0 = 21 + (–0.08×t)
0 = 21 – 0.08t
Collect like terms
0 – 21 = –0.08t
–21 = –0.08t
Divide both side by –0.08

<h3>t = 262.5 s</h3>
Therefore, it will take 262.5 s for the box to come to rest.
Learn more: brainly.com/question/14446351
To solve this problem we will begin by finding the pressure through density and average depth. Later we will find the Force, by means of the relation of the pressure and the area.

Here,
h = Depth average
= Density
Moreover,

Replacing,


Finally the force


