PHYSICS
COLLEGE

Answer: Given that the work function for sodium metal is 1.82 eV, what is the threshold frequency? 0. 1. 1. 0. 1. 1. 34. • When photons with a wavelength of 310 nm strike a magnesium plate, the maximum velocity of the ejected electrons is 3.45x10. 5 m/s. Calculate the binding energy of electrons to the magnesiumsurface. 1. 2. 2 +. 1.

HIGH SCHOOL

A traffic accident detective measures the skid marks left by a car, 825kg. He determines that the distance between the point that the driver slammed on the brakes and the point where the car came to a stop was 34.0 m. From a reference manual he determines that the coefficient of kinetic friction between the tires and the road under the prevailing conditions was 0.300. How fast was the car going when the driver applied the brakes? (This car was not equipped with anti-lock brakes.

Doing a force balance on the car:

ma = Fr

ma = μmg

a = μg

a = 0.3(9.81)

a = 29.43 m/s2

Using the formula:

2ax = v2

2(29.43)(34) = v2

v = 44.74 m/s = 161.05 km/h

The car was going 44.74 m/s or 161.05 kph when the brakes were applied.

ma = Fr

ma = μmg

a = μg

a = 0.3(9.81)

a = 29.43 m/s2

Using the formula:

2ax = v2

2(29.43)(34) = v2

v = 44.74 m/s = 161.05 km/h

The car was going 44.74 m/s or 161.05 kph when the brakes were applied.

HIGH SCHOOL

Recall the observed behavior of the compass during the mapping of the magnetic field. Which of the following descriptions best matches the behavior you observed? Two correct answers required for full credit. A. Where the field is strong the compass needle readily and quickly aligns with rapid oscillations around the equilibrium direction.

B. Where the field is strong the compass needle slowly oscillates around the final equilibrium position.

C. Where the field is weak the compass needle rapidly oscillates around the final equilibrium position.

D. Where the field is weak the compass needle slowly oscillates around the final equilibrium position.

E. Where the field is weak the compass needle readily and quickly aligns with rapid oscillations around the equilibrium direction.

Answer:

Option A & B

Explanation:

This is cause the compass needle is magnetized anointed in such a way that it responds to magnetic field strength.

MIDDLE SCHOOL

What are the names and symbols of common elements?

The names and symbols of some common elements are as follows:

Elements like Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Sulfur (S), and Phosphorus (P) are significantly found in the highest quantities. These elements make up about 99% of their living mass.

What are chemical elements?Chemical elements may be defined as the characteristics of atoms that possess a given number of protons in their nuclei, along with the number of neutrons including the pure substance typically consisting only of that species.

Along with some elements of living components, hydrogen and helium are the lightest elements found in the periodic table. Some common metallic elements are Copper (C), Iron (Fe), Gold (Au), Aluminium (Al), etc. are also had characteristic properties.

Therefore, the names and symbols of some common elements are well represented above.

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Hydrogen (H) and helium (He) are the lightest, and hydrogen, carbon (C), oxygen (O) and nitrogen (N) are found in organic molecules. Some of the metals include sodium (Na), gold (Au), silver (Ag), iron (Fe), copper (Cu) and aluminum (Al).

plz hit the hear and rate 5

MIDDLE SCHOOL

7. How long does it take a ball rolling down a hill to change its speed from 3 m/sec to 34.5 m/sec if it accelerates at a rate of 3.5 m/sec ??

The time elapsed is 9 seconds

Explanation:

The motion of the ball is a uniformly accelerated motion (a motion with constant acceleration), so we can use the following suvat equation:

where :

v is the final velocity of the ball

u is the initial velocity

a is the acceleration

t is the time elapsed

For the ball in this problem, we have:

u = 3 m/s is the initial velocity

v = 34.5 m/s is the final velocity

is the acceleration

Solving for t, we find the time taken for this change in velocity:

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MIDDLE SCHOOL

Why are some electromagnetic waves harmful to you but others are not?

Answer

They have different frequencies.

Explanations

Some electromagnetic wave have high frequency than others. hose with high frequency are more harmful than those with low frequency.

Waves with high frequency have a higher penetrating power and they can kill cells if exposed to it. This makes them harmful.

They have different frequencies.

Explanations

Some electromagnetic wave have high frequency than others. hose with high frequency are more harmful than those with low frequency.

Waves with high frequency have a higher penetrating power and they can kill cells if exposed to it. This makes them harmful.

Because for example a lightning bolt is an electromagnetic wave. Lighting bolts can hurt you or even kill you. But others waves cant harm you.

Hope this helps

Hope this helps

HIGH SCHOOL

The difference in the _____ of P waves and S waves is used to locate an earthquake’s epicenter. intensity

velocity

arrival times

speeds

The correct answer will be the C arrival times. The difference in the arrival times of P waves and S waves is used to locate an earthquake’s epicenter.

Answer:

arrival times

Explanation:

P waves (Primary waves) and S waves (Secondary waves) are the two types of mechanical waves emitted during an earthquake. The main difference between the two waves is their speed: in fact, P waves are much faster than S waves. Moreover, P waves can travel through solids and liquids, while S waves can travel through solids only. Because of their difference in speed, the S waves take more time than the P waves to go from the epicenter to the seismograph, therefore their arrival time is different and this difference in arrival time can be used to estimate the distance of the epicenter.

COLLEGE

An electron initially at rest accelerates through a potential difference of 1 V, gaining kinetic energy KEe, whereas a proton, also initially at rest, accelerates through a potential difference of - 1 V, gaining kinetic energy KEp. Which of the following relationships holds? a) Cannot be determined from the given information.

b) KEe > KEp

c) KEe < KEp

d) KEe = KEp

Answer:

d) KEe = KEp

Explanation:

According to the law of conservation of energy, the electric potential energy is converted into the kinetic energy of the particle:

Here, q is the particle's charge and V is the potential difference.

The charge of the electron is -e. So:

The charge of the proton is e. So:

So

HIGH SCHOOL

Write 806,000,000 in scientific notation. a. 8.06 x 108

b. 8.06 x 107

c. 8.06 x 1010

d. 8.06 x 109

A. 8.06 X 10^8

The decimal place is moved eight places to the right to get 8.06 so 10 is put to the power of eight. If it were put to the power of -8 the number would be smaller (0.0000000806). If you put 10^8 in a calculator and multiply it by 8.06 you will get the original number of 806,000,000

The decimal place is moved eight places to the right to get 8.06 so 10 is put to the power of eight. If it were put to the power of -8 the number would be smaller (0.0000000806). If you put 10^8 in a calculator and multiply it by 8.06 you will get the original number of 806,000,000

The correst answer is A. 8.06 x 10^8

MIDDLE SCHOOL

Consider a 2-kg bowling ball sits on top of a building that is 40 meters tall. It falls to the ground. Think about the amounts of potential and kinetic energy the bowling ball has: • as it sits on top of a building that is 40 meters tall.

• as it is half way through a fall off a building that is 40 meters tall and travelling 19.8 meters per second.

• as it is just about to hit the ground from a fall off a building that is 40 meters tall and travelling 28 meters per second.

4. What is the potential energy of the bowling ball as it sits on top of the building?

Answer:

5. What is the potential energy of the ball as it is half way through the fall, 20 meters high?

Answer:

7. What is the kinetic energy of the ball just before it hits the ground?

4) Potential energy at the top of the building: 784 J

5) Potential energy halfway through the fall: 392 J

7) Kinetic energy just before hitting the ground: 784 J

Explanation:

4)

The potential energy of an object is the energy possessed by the object due to its position in the gravitational field; it is given by

where

m is the mass of the object

g is the acceleration due to gravity

h is the height of the object relative to the ground

For the bowling ball, when it sits on top of the building, we have:

m = 2 kg

h = 40 m

Therefore, its potential energy is

5)

The potential energy of the ball when it is half way through the fall is:

where

m = 2 kg is the mass of the ball

is the acceleration due to gravity

h' = 20 m is the height of the ball relative to the ground

Substituting into the equation, we find:

7)

The kinetic energy of the ball just before hitting the ground can be found by applying the law of conservation of energy.

In fact, the total mechanical energy of the ball during the fall is constant, and it is given by:

where KE is the kinetic energy.

When the ball sits at the top of the building, KE = 0 (since the ball is not moving), so

When the ball is just about to hit the ground, its height is zero:

h = 0

This means that the potential energy is now zero:

PE = 0

And therefore, it means that all the mechanical energy is now kinetic energy, and so:

The kinetic energy can also be found by using the formula:

where

m = 2 kg is the mass of the ball

v = 28 m/s is the speed of the ball just before hitting the ground

Substituting,

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