PHYSICS
HIGH SCHOOL

2. rolling friction

3. fluid friction

Answer:

Answer:

Fluid Friction

Answer: 1 and 3 decuase1)how hard the surfaces push together, and 2)the types of surfaces involved (smooth vs. rough)

COLLEGE

The half-life of1 is 8.04 days. (a) Calculate the decay constant for this isotope. (b) Find the number of 1311 nuclei necessary to of 0.5 uCi produce a sample with an activity

Explanation:

Given that,

We need to calculate the decay constant

Using formula of decay constant

We need to calculate the number of nuclei

Where,

A= activity

ci = disintegration

Hence, This is the required solution.

HIGH SCHOOL

Compared to the gravitational force between two nucleons in an atom of helium, the nuclear force between the nucleons is

The gravitational force loses strength as a function of distance less rapidly than the nuclear force, but at very close ranges, such as those found within a single atom, the nuclear force is much stronger. So if the nucleons were each on opposite sides of a solar system, or even of a room, the force of gravity would be stronger, but in the described case the nuclear force is stronger.

HIGH SCHOOL

A circuit has a current of 3.6 A and a resistance of 5.0 Ω. What is the voltage applied to the circuit?

Answer: The correct answer is 18 V.

Explanation:

The mathematical expression from Ohm's law is as follows:

V=IR

Here, V is the voltage, R is the resistance and I is the current.

It is given in the problem that A circuit has a current of 3.6 A and a resistance of 5.0 Ω.

Put R= 5 ohm and I= 3.6 A in the above expression.

V= (3.6)(5)

V=18 V.

Therefore, the value of voltage is 18 V.

The key formula ===> Voltage = (current) x (resistance)

Plug in the numbers given ===> Voltage = (3.6 A) x (5.0 ohms)

Dooda multiplication ===> Voltage = 18 volts

COLLEGE

A nickel crystal's work function is measured to be 5.22 eV at 25°C. As the temperature increases by 300°C, the work function drops by 50 meV. By how much does this shift the threshold wavelength for photoelectric emission?

Answer:

The shift the threshold wavelength for photoelectric emission is 2.317 nm.

Explanation:

Given that,

Work function = 5.22 eV

Temperature = 25°C

Increased temperature = 300°C

Drop work function = 50 meV

We need to calculate the shift the threshold wavelength for photoelectric emission

Using formula of work function

The wavelength for initial temperature,

The wavelength for final temperature,

The change in wavelength is

Put the value into the formula

Hence, The shift the threshold wavelength for photoelectric emission is 2.317 nm.