One reason that adolescents go to bed much later than they did as children is that they

A block of 250-mm length and 48 × 40-mm cross section is to support a centric compressive load P. The material to be used is a b

Marrrta [24]

Answer:

153.6 kN

Explanation:

The elastic constant k of the block is

k = E * A/l

k = 95*10^9 * 0.048*0.04/0.25 = 729.6 MN/m

0.12% of the original length is:

0.0012 * 0.25 m = 0.0003 m

Hooke's law:

F = x * k

Where x is the change in length

F = 0.0003 * 729.6*10^6 = 218.88 kN (maximum force admissible by deformation)

The compressive load will generate a stress of

σ = F / A

F = σ * A

F = 80*10^6 * 0.048 * 0.04 = 153.6 kN

The smallest admisible load is 153.6 kN

8 0

3 years ago

Q15.17 Both wave intensity and gravitation obey inverse-square laws. Do they do so for the same reason?Discuss the reason for ea

s2008m [1.1K]

(a) Intensity obeys inverse square law from basis of light passing through a given surface.

(b) Gravitation obeys inverse square law from the basis of force between two masses.

(c) The maximum magnitude of the acceleration of the block is 126.75 m/s².

<h3>What is intensity?</h3>

Intensity is the ratio is ratio of power to area of a given surface.

I = P/A (W/m²)

where;

P is power
A is area

<h3>Universal gravitation law</h3>

$F = \frac{Gm_1m_2}{r^2}$

Intensity and gravitation do not obey inverse square law for same reason;

Intensity obeys inverse square law from basis of light passing through a given surface.
Gravitation obeys inverse square law from the basis of force between two masses.

<h3>Acceleration of the block</h3>

a = v²/A

a = (3.9²)/0.12

a = 126.75 m/s²

Learn more about acceleration here: brainly.com/question/605631

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7 0

2 years ago

PLEASE HELP ME

sashaice [31]

Given that,

Electrical energy of the motor = 2280 J

Kinetic energy = 1606 J

Wasted energy in thermal and sound energy = 550 J

To find,

The efficiency of the motor in percent.

Solution,

Efficiency is defined as the ratio of useful output energy to the total energy.

Total energy = 2280 J

Useful energy = 1606 J

$\eta=\dfrac{1606}{2280}\times 100\\\\=70.43\%$

So, the efficiency of the motor is 70.43%.

5 0

3 years ago

Q.4. What is the kinetic energy of a 10 kg car that is moving 4 m/s?

kodGreya [7K]

An object of mass $10 \mathrm{~kg}$ is moving with a uniform velocity of $4 \mathrm{~ms}^{-1}$ . The kinetic energy possessed by the object is $80 \mathrm{~J}$ .

Given:

Mass of an object $=10 \mathrm{~kg}$

Velocity $=4 \mathrm{~ms}^{-1}$

Kinetic Energy $=1 / 2 \times$ Mass of Object $\times(\text { Velocity })^{2}$

$\Rightarrow$ Kinetic Energy $=1 / 2 \times 10 \times 4 \times 4$

$\Rightarrow$ Kinetic Energy $=\underline{80 \mathbf{J}}$

What is Kinetic Energy?

In physics, an object's kinetic energy is the energy it has as a result of its motion.
It is defined as the amount of work required to accelerate a body of a given mass from rest to a certain velocity.
The body retains its kinetic energy after gaining it during acceleration until its speed changes.
Kinetic energy is present in a speeding bullet, a walking human, and electromagnetic radiation such as light. The energy associated with the continual, random bouncing of atoms or molecules is another type of kinetic energy.

Learn more about kinetic energy brainly.com/question/12669551

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6 0

2 years ago

A certain fan is capable of using 4800J of electrical energy each minute, converting 4000J of it into kinetic energy of the fan.

lapo4ka [179]

Answer:

Energy Ouput (Useful) / Total Energy Input = 4000 / 4800 = .833

E = 83% assuming 4800 is actually input to fan

8 0

2 years ago