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Firdavs [7]
3 years ago
9

In real machines, efficiency is always _____. less than 100% 100% more than 100%

Physics
1 answer:
skad [1K]3 years ago
3 0

In real machines, efficiency is always <em>less </em>than 100% .

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A wheel starts from rest and has an angular acceleration that is given by α (t) = (6.0 rad/s4)t2. After it has turned through 10
marissa [1.9K]

Answer:

75 rad/s

Explanation:

The angular acceleration is the time rate of change of angular velocity. It is given by the formula:

α(t) = d/dt[ω(t)]

Hence: ω(t) = ∫a(t) dt

Also, angular velocity is the time rate of change of displacement. It is given by:

ω(t) = d/dt[θ(t)]

θ(t) = ∫w(t) dt

θ(t) = ∫∫α(t) dtdt

Given that: α (t) = (6.0 rad/s4)t² = 6t² rad/s⁴. Hence:

θ(t) = ∫∫α(t) dtdt

θ(t) = ∫∫6t² dtdt =∫[∫6t² dt]dt

θ(t) = ∫[2t³]dt = t⁴/2 rad

θ(t) = t⁴/2 rad

At θ(t) = 10 rev = (10 *  2π) rad = 20π rad, we can find t:

20π = t⁴/2

40π = t⁴

t = ⁴√40π

t = 3.348 s

ω(t) = ∫α(t) dt = ∫6t² dt = 2t³

ω(t) = 2t³

ω(3.348) = 2(3.348)³ = 75 rad/s

7 0
3 years ago
Joe balances a stationary coin on the the tip of his finger 20 cm from the top of the table. How much work is Joe doing?
adell [148]

The work done by Joe is 0 J.

<u>Explanation</u>:

When a force is applied to an object, there will be a movement because of the applied force to a certain distance. This transfer of energy when a force is applied to an object that tends to move the object is known as work done.

The energy is transferred from one state to another and the stored energy is equal to the work done.

                                 W = F . D

where F represents the force in newton,  

          D represents the distance or displacement of an object.

Force = 0 N,   D = 20 cm = 0.20 m

                                 W = 0 \times 0.20 = 0 J.

Hence the work done by Joe is 0 J.

7 0
3 years ago
100 points!!! Please help!!!
Greeley [361]

Answer:

41°

Explanation:

Kinetic energy at bottom = potential energy at top

½ mv² = mgh

½ v² = gh

h = v²/(2g)

h = (2.4 m/s)² / (2 × 9.8 m/s²)

h = 0.294 m

The pendulum rises to a height of  above the bottom.  To determine the angle, we need to use trigonometry (see attached diagram).

L − h = L cos θ

cos θ = (L − h) / L

cos θ = (1.2 − 0.294) / 1.2

θ = 41.0°

Rounded to two significant figures, the pendulum makes a maximum angle of 41° with the vertical.

7 0
4 years ago
An experiment is set up to test the angular resolution of an optical device when red light (wavelength ????r ) shines on an aper
Neko [114]

Explanation:

As per Rayleigh criterion, the angular resolution is given as follows:

\theta=\frac{1.22 \lambda}{D}

From this expression larger the size of aperture, smaller will be the value of angular resolution and hence, better will be the device i.e. precision for distinguishing two points at very high angular difference is higher.

4 0
4 years ago
The synodic period for a planet is different from its sidereal period because
IrinaK [193]
<span>Earth (and hence the observer) moves.</span>
5 0
3 years ago
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