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Lemur [1.5K]
3 years ago
5

Identify the type of friction in each situation described below:

Physics
1 answer:
-BARSIC- [3]3 years ago
8 0

Answer:

A . static frictional force

B. kinectic friction

C.. Rolling friction

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A ball is dropped from a cliff. determine how far the ball fell after 7.5 seconds
grin007 [14]

Answer:

The ball fell 275.625 meters after 7.5 seconds

Explanation:

<u>Free fall </u>

If an object is left on free air (no friction), it describes an accelerated motion in the vertical direction, powered exclusively by the acceleration of gravity. The formulas needed to compute the different magnitudes involved are

V_f=gt

\displaystyle y=\frac{gt^2}{2}

Where V_f is the final speed of the object in free fall, assumed positive downwards, t is the time elapsed since the release and y is the vertical distance traveled by the object

The ball was dropped from a cliff. We need to calculate the vertical distance the ball went down in t=7.5 seconds. We'll use the formula

\displaystyle y=\frac{gt^2}{2}

\displaystyle y=\frac{(9.8)(7.5)^2}{2}

Y=275.625\ m

5 0
3 years ago
A dolphin in an aquatic show jumps straight up out of the water at a velocity of 15.0 m/s. (a) List the knowns in this problem.
astra-53 [7]

Answer:

a)

Y0 = 0 m

Vy0 = 15 m/s

ay = -9.81 m/s^2

b) 7.71 m

c) 3.06 s

Explanation:

The knowns are that the initial vertical speed (at t = 0 s) is 15 m/s upwards. Also at that time the dolphin is coming out of the water, so its initial position is 0 m. And since we can safely assume this happens in Earth, the acceleration is the acceleration of gravity, which is 9.81 m/s^2 pointing downwards

Y(0) = 0 m

Vy(0) = 15 m/s

ay = -9.81 m/s^2 (negative because it points down)

Since acceleration is constant we can use the equation for uniformly accelerated movement:

Y(t) = Y0 + Vy0 * t + 1/2 * a * t^2

To find the highest point we do the first time derivative (this is the speed:

V(t) = Vy0 + a * t

We equate this to zero

0 = Vy0 + a * t

0 = 15 - 9.81 * t

15 = 9.81 * t

t = 0.654 s

At this time it will have a height of:

Y(0.654) = 0 + 15 * 0.654 - 1/2 * 9.81 * 0.654^2 = 7.71 m

The doplhin jumps and falls back into the water, when it falls again it position will be 0 again. So we can equate the position to zero to find how long it was in the air knowing that it started the jump at t = 0s.

0 = Y0 + Vy0 * t + 1/2 * a * t^2

0 = 0 + 15 * t - 1/2 * 9.81 t^2

0 = 15 * t - 4.9 * t^2

0 = t * (15 - 4.9 * t)

t1 = 0 This is the moment it jumped into the air

0 = 15 - 4.9 * t2

15 = 4.9 * t2

t2 = 3.06 s This is the moment when it falls again.

3.06 - 0 = 3.06 s

5 0
3 years ago
Will mark BRAINLIEST!!!!
REY [17]

Answer:

Atoms found in nature are either stable or unstable. ... An atom is unstable (radioactive) if these forces are unbalanced; if the nucleus has an excess of internal energy. Instability of an atom's nucleus may result from an excess of either neutrons or protons

7 0
2 years ago
What is the frequency of a clock waveform whose period is 750 microseconds?
Allushta [10]
Use this formula to find your answer...

Determine the frequency of a clock waveform whose period is 2us or (micro) and 0.75ms

frequency (f)=1/( Time period).

Frequency of 2 us clock =1/2*10^-6 =10^6/2 =500000Hz =500 kHz.

Frequency of 0..75ms clock =1/0.75*10^-3 =10^3/0.75 =1333.33Hz =1.33kHz.

6 0
3 years ago
A light source radiates 60.0 W of single-wavelength sinusoidal light uniformly in all directions. What is the amplitude of the m
Anna35 [415]

To solve this problem it is necessary to take into account the concepts of Intensity as a function of Power and the definition of magnetic field.

The intensity depending on the power is defined as

I = \frac{P}{4\pi r^2},

Where

P = Power

r = Radius

Replacing the values that we have,

I = \frac{60}{(4*\pi (0.7)^2)}

I = 9.75 Watt/m^2

The definition of intensity tells us that,

I = \frac{1}{2}\frac{B_o^2 c}{\mu}

Where,

B_0 =Magnetic field

\mu = Permeability constant

c = Speed velocity

Then replacing with our values we have,

9.75 = \frac{Bo^2 (3*10^8)}{(4\pi*10^{-7})}

Re-arrange to find the magnetic Field B_0

B_o = 2.86*10^{-7} T

Therefore the amplitude of the magnetic field of this light is B_o = 2.86*10^{-7} T

6 0
3 years ago
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