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3 years ago

A wave has a wavelength of 7 mm and a frequency of 9 hertz. What is its speed?

1 answer:

8 0

Speed of wave = Frequency x Wavelength
so Speed = 0.7 x 9 = 6.3

remember the calculations must be done in their Basic SI units.
therefore, you have to convert 7 mm to meters which becomes 0.7 meters

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In a 49 s interval, 595 hailstones strike a glass window of an area of 0.954 m at an angle of 25° to the window surface. Each ha

eduard

Average force on the window: 0.32 N

Explanation:

The average force exerted on the window is given by Newton's second law

$F=\frac{\Delta p}{\Delta t}$

where

$\Delta p$ is the net change in momentum of the hailstones in a time interval of $\Delta t$

In order to find the change in momentum, we have to consider only the component of the hailstone's momentum perpendicular to the window, therefore:

$p_i =m u sin \theta$ is the initial momentum of one hailstone, with

m = 7 g = 0.007 kg is the mass

$u=4.5 m/s$ is the initial speed

$\theta=25^{\circ}$ is the angle with the window

The final momentum is

$p_f = mv sin \theta$

where

v = 4.5 m/s is the final speed (the collision is elastic so the speed is equal, while the direction changes)

$\theta=-25^{\circ}$ (after the rebound, the direction has changed)

So the change in momentum of 1 hailstone is

$\Delta p = mv sin(-25^{\circ})-mu sin(25^{\circ})=-2mu sin(25^{\circ})=-0.0266 kg m/s$

We are interested only in the magnitude, so

$\Delta p = 0.0266 kg m/s$

There are 595 hailstones hitting the window in 49 s, so the total change in momentum is

$\Delta p = 595\cdot 0.0266 = 15.8 kg m/s$

And therefore, the average force on the window is

$F=\frac{\Delta p}{\Delta t}=\frac{15.8}{49}=0.32 N$

Learn more about force:

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#LearnwithBrainly

3 0

2 years ago

A parallel-plate capacitor connected to a battery becomes fully charged. After the capacitor from the battery is disconnected, t

Valentin [98]

Answer:

C.)The energy stored in the capacitor doubles its original value.

Explanation:

The capacitance of a capacitor is given by:

C₁ = ∈A/d...............................(1)

If the distance between the plates is doubled

C₂ = ∈A/2d.............................(2a)

From equations (1) and (2), the relationship between C₁ and C₂ is:

C₂ = C₁/2....................................(2b)

The original Energy stored in the capacitor is given by :

E₁ = Q²/2C₁...............................(3)

On doubling the separation between the capacitance plates

E₂ = Q²/2C₂...............................(4a)

E₂ = Q²/2 * 1/C₂........................(4b)

Putting equation (2b) into (4b)

E₂ = Q²/2 * 2/C₁

E₂ = Q²/C₁.....................................(5)

Comparing equations (3) and (5)

E₂ = 2E₁

Therefore, the energy stored in the capacitor doubles its original value

4 0

3 years ago

Two students push on a 5-kg cart from opposite sides

sweet-ann [11.9K]

Answer:

nothing will happen the cart will be broken or as it is

4 0

2 years ago

Read 2 more answers

When a gas is cooled, the particles begin to move more______(Quickly/slowly). When the temperature drops below the____ (melting

bija089 [108]

Slowly; Boiling Point; Decrease; Decrease; Vibrate in place.

As temperature drops, so does thermal energy, and particle motion drops. The same trends in temperature, thermal energy, and motion applys to phases in decreasing order: gas>liquid>solid. The particle motion is always vibrations in place for solids because they are very tightly packed compared to liquids and gases.

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3 years ago

2. Elements in the same group have similar properties because they have O the same number of protons O the same number of valenc

NARA [144]

The same number of valence electrons

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2 years ago