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hjlf
3 years ago
11

If the actual frictional force is equal to 1 lb., then how much effort (force) would be required to drag a 90 lb. box up the pla

ne?
10+ lb.

10- lb.

9+ lb.

9- lb.
Physics
1 answer:
MissTica3 years ago
5 0
It's 10+ lb ans please tell if i am wrong
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A mass hanging from a spring oscillates with a period of 0.35 s. Suppose the mass and spring are swung in a horizontal circle, w
Annette [7]

Answer:

66 rpm

Explanation:

The period of oscillation is given by

T=2\pi \sqrt{\frac {m}{k}}

\frac {k}{m}=\frac {4\pi^{2}}{T^{2}} where  T is time period of oscillation which is given as 0.35 s, k s spring constant and m is the mass of the object attached to the spring.

Also, net force is given by

Net force=m\omega^{2} L

\omega=\sqrt{\frac {k\triangle L}{mL}} where \triangle L is the elongation, L is original length, \omega is the angular velocity

Substituting the equation of \frac {k}{m} into the above we obtain

\omega=\sqrt {\frac {4\pi^{2}\triangle L}{T^{2} L}}

\omega=\sqrt {4\pi^{2}\times 0.15L}{0.35^{2}\times L}}=6.952763\approx 6.95 rad/s

6.95\times\frac {60 s}{2\pi rad}\approx 66 rpm

6 0
4 years ago
What is the frequency of a microwave of wavelength 3cm?
navik [9.2K]

Frequency = (speed) / (wavelength)

Speed = 3 x 10⁸ m/s

Wavelength = 3 cm = 0.03 m

Frequency = (3 x 10⁸  m/s) / (0.03 m)

Frequency = (3 x 10⁸ / 0.03) (m / m-s)

Frequency =  1 x 10¹⁰ Hz (10 Gigahertz)

5 0
3 years ago
Which graph shows the correct relationship between kinetic energy and speed?
Mamont248 [21]

Answer: D

Explanation:

Kinetic energy = 1/2mV^2

From the formula above, we can deduce that kinetic energy is proportional to the square of speed. That is,

K.E = V^2

Graphically, the relationship isn't linear but a positive exponential. Therefore, option D is the correct answer.

3 0
3 years ago
What are all of the si units
mina [271]

Here you go

There are seven basic units in the SI system: the meter (m), the kilogram (kg), the second (s), the kelvin (K), the ampere (A), the mole (mol), and the candela (cd).


Hope it helps you

Please mark me as Brainsliest

5 0
4 years ago
The intensity of an earthquake wave passing through the earth is measured to be 2.5×106 j/(m2⋅s) at a distance of 43 km from the
vampirchik [111]

r₁ = distance of the point from the source = 43 km = 43000 m

I₁ = intensity of earthquake wave at distance "r₁" = 2.5 x 10⁶ W/m²

r₂ = distance of the point from the source = 1.5 km = 1500 m

I₂ = intensity of earthquake wave at distance "r₂" = ?

we know that , for a constant power , the intensity of wave is inversely proportional to the distance from the source .

I α 1/r²             where I = intensity of wave , r = distance from source

hence we can write

I₁/I₂ = r₂²/r₁²

inserting the values

(2.5 x 10⁶) /I₂ = (1500/43000)²

I₂ = 2.1 x 10⁹ W/m²

4 0
3 years ago
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