Answer:
o The result of a chemical change is a different composition; in a physical change, the composition remains the same.
Explanation:
In a chemical change, new kinds of matter are produced although the atoms are the same.
For physical changes, no new kinds of matter formed. Only the state of substances changes.
- Most chemical changes are usually irreversible
- Physical changes are reversible in most parts.
- Changes in state and form are salient characteristics of physical changes.
- When new products are formed from the reactants, it is an indicator of a chemical change.
Answer:
Speed of the wave is 7.87 m/s.
Explanation:
It is given that, tapping the surface of a pan
of water generates 17.5 waves per second
We know that the number of waves per
second is called the frequency of a wave.
So, f= 17.5 HZ
Wavelength of each wave,
A = 45 cm = 0.45 m
Speed of the wave is given by:
175 × 0.45
V= 7.87 m/s
So, the speed of the wave is 7.87 m/s
Hence, this is the required solution.
Answer:
14 m/s
Explanation:
Using the principle of conservation of energy, the potential energy is converted to kinetic energy, assuming any losses.
Kinetic energy is given by ½mv²
Potential energy is given by mgh
Where m is the mass, v is the velocity, g is acceleration due to gravity and h is the height.
Equating kinetic energy to be equal to potential energy then
½mv²=mgh
V
Making v the subject of the formula
v=√(2gh)
Substituting 9.81 m/s² for g and 10 m for h then
v=√(2*9.81*10)=14.0071410359145 m/s
Rounding off, v is approximately 14 m/s
Answer:
B. X-rays
Explanation:
From the given choices, x-rays will have the highest energy of the given waves.
The energy of electromagnetic waves is highly dependent on their frequency and wavelength.
Electromagnetic waves with a high frequency and small wavelength will have higher energy compared to those with low frequency and high wavelength.
X-rays are one the most energetic waves on the periodic table. They have a very high frequency and low wavelength.
Answer:
B) Friction
Explanation:
Friction is a force that acts when an object is sliding along a surface. Microscopically, this force is due to the fact that the two surfaces are not perfectly smooth, but they have "imperfections" that cause a force that opposes the motion of the object.
For an object sliding on a flat surface, the force of friction has magnitude:
where
is the coefficient of kinetic friction
m is the mass of the object
g is the acceleration of gravity
The direction of the force of friction is always opposite to the direction of motion of the object.
In reality, friction also acts if the object is at rest and it is pushed by a force; in this case, we talk about static friction, and its magnitude is
where 
is called coefficient of static friction, and it is generally larger than the coefficient of kinetic friction.
