Answer:
f = 0.5 Hz
v = 8 m/s
Explanation:
f = 1/T
f = 1/(2) = 0.5 Hz
v = λf
v = (2)(4) = 8 m/s
Answer:
Both energies are equal when the rock has fallen 20 m or equivalently when it is at a height of 20 m.
Explanation:
Potential and Kinetic Energy
The gravitational potential energy is the energy an object has due to its height above the ground. The formula is
Where:
m = mass of the object
g = acceleration of gravity (9.8~m/s^2)
h = height
Note we can also use the object's weight W=mg into the formula:
The kinetic energy is the energy an object has due to its speed:
Where v is the object's speed.
Initially, the object has no kinetic energy because it's assumed at rest.
The W=30 N rock falls from a height of h=40 m, thus:
Since the sum of the kinetic and potential energies is constant:
U' + K' = 1,200 J
Here, U' and K' are the energies at any point of the motion. Since both must be the same:
U' = K' = 600 J
U'=Wh'=600
Solving for h':
Both energies are equal when the rock has fallen 20 m or equivalently when it is at a height of 20 m.
b.exists as a liquid
c.exists as a crystalline solid
d.exists as an amorphous solid
Answer:
c.exists as a crystalline solid
Explanation:
Amongst all the three phases, it is solid phase which is the most compact because the atoms within the solids are bound with a very strong force of attraction. But, solids can exist as either crystalline solid or amorphous solid. Between these two type of solids, it is crystalline solids which are very well packed and the inter atomic distance between their two atoms is the least. It is due to the reason that the atoms within a crystalline solid are arranged in proper order in the form of stacks. But, in amorphous solids the atoms are not arranged properly i.e. their arrangement is random which leads to the increased inter atomic distance. Second comes liquid phase, in liquids the inter atomic forces are intermediate between solids and gases. Atoms in a gas are bound with the weakest force of attraction known as van der Waals that is why the distance between the atoms of a gas is the highest.
I live in the city. It's always warmer in the city, compared to other areas, even at night. Why is that?
A.) The rain shadow effect makes surrounding areas cool and moist and the city warm and dry.
B.) Buildings absorb and retain heat from the Sun, producing the urban heat island effect.
C.) Lake effect snow only affects areas outside of the city.
D.) The city receives lake effect snow.