You are given a copper bar of dimensions 3 cm × 5 cm × 8 cm and asked to attach leads to it in order to make a resistor.

During the course of a demonstration the professor is called away. When he returns he finds a beaker of water that was at room t

Yanka [14]

Answer:

Either heat added or mechanical work done.

Explanation:

Since he found stirring rod on the desk and a cigarette lighter. This means that the beaker was probably either heated with the aid of fire from the lighter.

Also, the stirring rod could have been used to stir the water which will increase the kinetic energy which also means an increase in temperature.

Thus, it's either heat was added or mechanical work was done as a result of stirring.

5 0

2 years ago

A small sphere is hung by a string from the ceiling of a van. When the van is stationary, the sphere hangs vertically. However,

Paraphin [41]

Answer: 42.49 $m/s^{2}$

Explanation:

To solve this, we need to keep in mind the following:

While the sphere hangs it is under the effect of gravity. It is creating a Angle of 90° taking the roof as a reference.

Gravity can be noted as a Acceleration Vector. The magnitud for Earth's Gravity is a constant: 9.81 $m/s^{2}$

The acceleration of the Van will affect the sphere also, but this accelaration will be on the X-axis and perpendicular to the gravity. Because this two vectors are taking action under the sphere they will create a angle. This angle can be measured as a relation of the two magnitudes.

Tangent (∅) = Opossite Side / Adyacent Side

By trigonometry, we know the previous formula. This formula allows us to find the Tangent of a angle as a relation between the two perpendiculars magnitudes. In this case the Opossite Side will be the Gravity Accelaration, while the Adyancent Side is the Van's Acceleration.

(1) Tangent (∅) = Gravity's Acceleration (G) / Van's Acceleration (Va)

Searching for the Va in (1)

Va = G/Tan(∅)

Where ∅ in this case is equal to 13.0°

Va = 9.81 $m/s^{2}$ / Tan(13.0°)

Va = 42.49 $m/s^{2}$

The vans acceleration need to be 42.49 $m/s^{2}$ to create an angle of 13° with the Van's Roof

3 0

3 years ago

A 34.0 %-efficient electric power plant produces 800 MW of electric power and discharges waste heat into 20∘C ocean water. Suppo

mojhsa [17]

Answer:

77647

Explanation:

$\eta$ = Efficiency = 34%

Power used in 1 home = 0.02 MW

Total power is

$P=\dfrac{800}{\eta}\\\Rightarrow P=\dfrac{800}{0.34}\\\Rightarrow P=2352.94117\ MW$

Waste of power

$2352.94117-800=1552.94117\ W$

Number of homes would be given by

$n=\dfrac{1552.94117}{0.02}=77647.0585\ homes$

The number of homes that could be heated with the waste heat of this one power plant is 77647

8 0

2 years ago

What is the temperature of a 3.72 mm cube (e=0.288) that radiates 56.6 W?

blsea [12.9K]

Answer:

The temperature is 2541.799 K

Explanation:

The formula for black body radiation is given by the relation;

Q = eσAT⁴

Where:

Q = Rate of heat transfer 56.6

σ = Stefan-Boltzman constant = 5.67 × 10⁻⁸ W/(m²·k⁴)

A = Surface area of the cube = 6×(3.72 mm)² = 8.3 × 10⁻⁵ m²

e = emissivity = 0.288

T = Temperature

Therefore, we have;

T⁴ = Q/(e×σ×A) = 56.6/(5.67 × 10⁻⁸ × 8.3 × 10⁻⁵ × 0.288) = 4.174 × 10¹⁴ K⁴

T = 2541.799 K

The temperature = 2541.799 K.

7 0

3 years ago

A 5.0 kg chunk of putty moving at 10m/s collides and sticks to a 7.0 kg bowling ball that is initially at rest.What is the total

Flura [38]

Answer:

Total momentum = 50kgm/s

Explanation:

Given the following data;

Mass, M1 = 5kg

Mass, M2 = 7kg

Velocity, V1 = 10m/s

Velocity, V2 = 0m/s (since it's at rest).

To find the total momentum;

Momentum can be defined as the multiplication (product) of the mass possessed by an object and its velocity. Momentum is considered to be a vector quantity because it has both magnitude and direction.

Mathematically, momentum is given by the formula;

$Momentum = Mass * Velocity$

The law of conservation of momentum states that the total linear momentum of any closed system would always remain constant with respect to time.

Total momentum = M1V1 + M2V2

Substituting into the equation, we have;

Total momentum = 5*10 + 7*0

Total momentum = 50 + 0

Total momentum = 50 kgm/s

Therefore, the total momentum of the bowling ball and the putty after they collide is 50 kgm/s.

8 0

3 years ago