A kid applies a force of 70 N to a ball over 1.1 meters. How much work did he do on the ball?

A 3.20 kg block starts at rest and slides a distance d down a frictionless β = 30.0 ◦ incline, where it runs into a spring with

Virty [35]

Answer:

Explanation:

a ) work done by gravitational force

= mg sinθ ( d + .21)

Potential energy stored in compressed spring

= 1/2 k x²

= .5 x 431 x ( .21 )²

= 9.5

According to conservation of energy

mg sinθ ( d + .21) = 9.5

3.2 x 9.8 x sin 30( d + .21 ) = 9.5

d = 40 cm

b )

As long as mg sin30 is greater than kx ( restoring force ) , there will be acceleration in the block.

mg sin30 = kx

3.2 x 9.8 x .5 = 431 x

x = 3.63 cm

When there is compression of 3.63 cm in the spring , block will have maximum velocity. there after its speed will start decreasing.

7 0

3 years ago

A heat engine operates between two reservoirs at 300K. During each cycle, it absorbs 200 calories from the high temperature rese

yanalaym [24]

(a) Zero

The maximum efficiency (Carnot efficiency) of a heat engine is given by

$\eta=1-\frac{T_C}{T_H}$

where

$T_C$ is the low-temperature reservoir

$T_H$ is the high-temperature reservoir

For the heat engine in the problem, we have:

$T_C = 300K$

$T_H = 300K$

Therefore, the maximum efficiency is

$\eta=1-\frac{300}{300}=0$

(b) Zero

The efficiency of a heat engine can also be rewritten as

$\eta = \frac{W}{Q_H}$

where

W is the work performed by the engine

$Q_H$ is the heat absorbed from the high-temperature reservoir

In this problem, we know

$\eta=0$

Therefore, since the term $Q_H$ cannot be equal to infinity, the numerator of the fraction must be zero as well, which means

W = 0

So the engine cannot perform any work.

5 0

3 years ago

When a rocket is 4 kilometers high, it is moving vertically upward at a speed of 400 kilometers per hour. At that instant, how f

Y_Kistochka [10]

Answer:

The angle of elevation of the rocket is increasing at a rate of 48.780º per second.

Explanation:

Geometrically speaking, the distance between the rocket and the observer ( $r$ ), measured in kilometers, can be represented by a right triangle:

$r = \sqrt{x^{2}+y^{2}}$ (1)

Where:

$x$ - Horizontal distance between the rocket and the observer, measured in kilometers.

$y$ - Vertical distance between the rocket and the observer, measured in kilometers.

The angle of elevation of the rocket ( $\theta$ ), measured in sexagesimal degrees, is defined by the following trigonometric relation:

$\tan \theta = \frac{y}{x}$ (2)

If we know that $x = 5\,km$ , then the expression is:

$\tan \theta = \frac{y}{5}$

And the rate of change of this angle is determined by derivatives:

$\sec^{2}\theta \cdot \dot \theta = \frac{1}{5}\cdot \dot y$

$\frac{\dot \theta}{\cos^{2}\theta} = \frac{\dot y}{5}$

$\frac{\dot \theta\cdot (25+y^{2})}{25} = \frac{\dot y}{5}$

$\dot \theta = \frac{5\cdot \dot y}{25+y^{2}}$

Where:

$\dot \theta$ - Rate of change of the angle of elevation, measured in sexagesimal degrees.

$\dot y$ - Vertical speed of the rocket, measured in kilometers per hour.

If we know that $y = 4\,km$ and $\dot y = 400\,\frac{km}{h}$ , then the rate of change of the angle of elevation is:

$\dot \theta = 48.780\,\frac{\circ}{s}$

The angle of elevation of the rocket is increasing at a rate of 48.780º per second.

3 0

3 years ago

A large water tank is 3.75 m high and filled to the brim, the top of the tank open to the air. A small pipe with a faucet is att

Degger [83]

Answer:

7.16 m /s

Explanation:

The depth of the small pipe attached with the side wall of tank from the surface of water

h =( 3.1 - .48 )m

= 2.62 m

velocity of flow of water= √ 2 g h

= √ 2 x 9.8 x 2.62

= 7.16 m /s

#need any question answered within secs/mins, hit me up and I got you!

#branilest

:) <3

5 0

3 years ago

Resistors and reactors, for use over 600 volts, shall not be installed in close enough proximity to combustible materials to con

suter [353]

Resistors and reactors, for use over 600 volts, shall not be installed in close enough proximity to combustible materials to constitute a fire hazard and shall have a clearance of not less than<u> 300 mm </u>from combustible materials.

Explanation:

The hazards associated with high power industrial resistors are primarily due to their open construction, which is necessary for cooling.
The exposed conductors which make up the resistors can be not only a shock hazard but also a thermal burn hazard.
When a resistor fails, it either goes open or the resistance increases. When the resistance increases, it can burn the board, or burn itself up.
Avoid touching non-flammable resistors in operation; the surface temperature ranges from approximately 350 °C to 400°C when utilized at the full rated value. Maintaining a surface temperature of 200°C or less will extend resistors service life.
Do not apply power to a circuit while measuring resistance. When you are finished using an ohmmeter, switch it to the OFF position if one is provided and remove the leads from the meter.
Always adjust the ohmmeter for 0 (or in shunt ohmmeter) after you change ranges before making the resistance measurement.

4 0

3 years ago