Answer:
The time for the cake to cool off to room temperature is
approximately 30 minutes.
Let 
= 
F be the temperature and T that of the body
Explanation:
Our Tm = 70, the initial-value problem is
= <em>k</em>(T − 70), T(0) = 300
Solving the equation, we get
= <em>kdt</em>
In [T-70]= <em>kt </em>+
T = 70 + 
Finding he value for using the initial value of T (0)= 300, therefore we get:
300=70+
= 230 therefore
T= 70+ 230
Finding the value for <em>k </em>using T (3) = 200, therefore we get
T (3) = 200
= 
<em>K </em>= 
in
= -0.19018
Therefore
T(t) = 70+230
The three properties of electromagnetic waves are; they travel at the speed of light, they include ultraviolet waves, and they can transfer energy through empty space.
<h2>Further Explanation</h2><h3>A wave</h3>
- A wave is a transmission of a disturbance. It involves transmission of energy from one point which is the source to another point.
- Waves may be classified depending on the need for a transmission medium or based on the vibration of particles relative to the direction of wave motion.
- Waves may be either transverse or longitudinal based on the direction of wave motion relative to the vibration of particles
- Additionally waves may be classified as either electromagnetic wave or mechanical based on the need for a transmission medium.
<h3>Electromagnetic waves </h3>
- Electromagnetic waves are types of waves that do not require a material medium for transmission.
- All waves of the electromagnetic spectrum are electromagnetic transverse waves that do not require a material medium for transmission.
- They include; radio waves, microwaves, infrared, visible light, ultra-violet, x-rays, and gamma rays.
- All waves of the electromagnetic spectrum travel with a speed of light, 3.0 x10^8 m/s.
- Additionally, electromagnetic waves possess energy that is given by; E = hf; where h is the plank's constant and f is the frequency.
keywords: Wave, electromagnetic wave, electromagnetic spectrum
<h2>Learn more about: </h2>
Level: High school
Subject: Physics
Topic: Electromagnetic spectrum
Sub-topic: Properties of an electromagnetic waves
<span>you can look at magnesium, it can react with oxygen to form oxides. (chemical) it is malleable and a solid at room temperature. (physical)
</span><span>to measure its density, the mass and volume can be worked out and from this density too. look up the equation, it is quite easy :)
</span><span>physical changes -- it can be melted, and oxidized
</span><span>the chemical changes of oxidation magnesium looses electrons to form oxides, this is a chemical reaction- chemical change..--- use to get the density use (rho) or density D = M/V</span>
The emerging velocity of the bullet is <u>71 m/s.</u>
The bullet of mass <em>m</em> moving with a velocity <em>u</em> has kinetic energy. When it pierces the block of wood, the block exerts a force of friction on the bullet. As the bullet passes through the block, work is done against the resistive forces exerted on the bullet by the block. This results in the reduction of the bullet's kinetic energy. The bullet has a speed <em>v</em> when it emerges from the block.
If the block exerts a resistive force <em>F</em> on the bullet and the thickness of the block is <em>x</em> then, the work done by the resistive force is given by,
This is equal to the change in the bullet's kinetic energy.
If the thickness of the block is reduced by one-half, the bullet emerges out with a velocity v<em>₁.</em>
Assuming the same resistive forces to act on the bullet,
Divide equation (2) by equation (1) and simplify for v<em>₁.</em>
Thus the speed of the bullet is 71 m/s
<h3><u>Answer and Explanation</u>;</h3>
- input force refers to the force exerted on a machine, also known as the effort, while the output force is the force machines produce or the Load. The ratio of output force to input force gives the mechanical advantage of a simple machine
- <em><u>The output force exerted by the rake must be less than the input force because one has to use force while raking. The force used to move the rake is the input force. </u></em>
- <em><u>The rake is not going to be able to convert all of the input force into output force, the force the rake applies to move the leaves, because of friction.</u></em>
