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2 years ago

A boy is trying to roll a bowling ball up a hill, as shown in the image below. If

Physics

1 answer:

kherson [118]2 years ago

4 0

The minimum initial velocity that the ball must have for it to reach the top of the hill is 21 m/s. The correct option is D.

<h3>What is mechanical energy?</h3>

The mechanical energy is the sum of kinetic energy and the potential energy of an object at any instant of time.

M.E = KE +PE

A boy is trying to roll a bowling ball up a hill. The friction is ignored. The ball must have to reach the top of the hill with a velocity. The acceleration due to gravity, g = 9.8 m/s²

The conservation of energy principle states that total mechanical energy remains conserved in all situations where there is no external force acting on the system.

M.E bottom of hill = M.E on top of hill

Kinetic energy + Potential energy = Kinetic energy + Potential energy

1/2 mu² + 0 = 0 + mgh

At the top of hill, the velocity will become zero. So, final kinetic energy is zero.

Substituting the values, we have

1/2 x u² = 9.8 x 22.5

u = sqrt [2 x9.8 x 22.5 ]

u= 21 m/s

Thus, the minimum initial velocity that the ball must have for it to reach the top of the hill is 21 m/s.

Learn more about mechanical energy.

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Light with a frequency of 7.30 x 1014 hz lies in the violet region of the visible spectrum. What is the wavelength of this frequ

Leona [35]

From the theory we know that:

c = λ / T

f = 1 / T

Where:

c = 3. $10^{8}$ / m (the speed of light)

λ is the wavelengh (in meters)

T is the period (in seconds)

f is the frequency (in Hz)

We were told that:

f = 7.30 . $10^{14}$

And we want to find out the value of λ.

c = λ / T

c = λ . 1/T

Swaping 1/T = f

c = λ . f

λ = c / f

λ = 3 . $10^{8}$ / 7.30 . $10^{14}$

λ = 4.12 $10^{-7}$ m

Response: 4.12 $10^{-7}$ m = 412 nm

:-)

6 0

3 years ago

How far will a car travel in 30 min at 40 m/s? (kilometres)

kondor19780726 [428]

Answer:

72km

Explanation:

30 mins --> 30 x 60 s = 1800 s

Distance --> Speed x Time

= 40m/s x 1800s

= 72 000 m

= 72 km (1km is 1000m)

6 0

3 years ago

A solenoidal coil with 25 turns of wire is wound tightly around another coil with 300 turns. The inner solenoid is 25.0 cm long

joja [24]

Answer:

$5.65487\times 10^{-8}\ Wb$

$1.17\times 10^{-5}\ H$

-0.020475 V

Explanation:

$\mu_0$ = Vacuum permeability = $4\pi \times 10^{-7}\ H/m$

$N_1$ = Number of turns of coil = 25

$N_2$ = Number of turns of coil 2 = 300

$\frac{di_2}{dt}$ = Rate of current increased = $1.75\times 10^3\ A/s$

d = Diameter = 2 cm

r = Radius = $\frac{d}{2}=\frac{2}{2}=1\ cm$

A = Area = $\pi r^2$

Magnetic field in the solenoid is given by

$B=\mu_0\frac{N_2}{l}I\\\Rightarrow B=4\pi\times 10^{-7}\frac{300}{0.25}\times 0.12\\\Rightarrow B=0.00018\ T$

Magnetic flux is given by

$\phi=BA\\\Rightarrow \phi=0.00018\times \pi\times 0.01^2\\\Rightarrow \phi=5.65487\times 10^{-8}\ Wb$

The average magnetic flux through each turn of the inner solenoid is $5.65487\times 10^{-8}\ Wb$

Mutual inductance is given by

$L=\frac{N_1\phi}{i_1}\\\Rightarrow L=\frac{25\times 5.65487\times 10^{-8}}{0.12}\\\Rightarrow L=1.17\times 10^{-5}\ H$

The mutual inductance of the two solenoids is $1.17\times 10^{-5}\ H$

Induced emf is given by

$V=-L\frac{di_2}{dt}\\\Rightarrow V=-1.17\times 10^{-5}\times 1.75\times 10^3\\\Rightarrow V=-0.020475\ V$

The emf induced in the outer solenoid by the changing current in the inner solenoid is -0.020475 V

5 0

3 years ago

The moon’s rotational period and revolution period are equal. What is the result of this? Enter your answer in the space provide

beks73 [17]

Answer The Moon has synchronous rotation: it's rotation period is the same as its period of revolution

Explanation:

The Moon has synchronous rotation: it's rotation period is the same as its period of revolution

5 0

3 years ago

Kyle lays a mirror flat on the floor and aims a laser at the mirror. The laser beam reflects off the mirror and strikes an adjac

fgiga [73]

Answer:

θr = 55.2 °

Explanation:

The law of reflection states that the angle of incidence and the angles of reflection is the same.

Let's use trigonometry to find the angle between the reflected ray, where the horizontal distance x = 55.9 cm and the vertical distance is y = 38.9 cm

tan θ = y / x

tan θ = 38.9 / 55.9

θ = tan⁻¹ (0.6959)

θ = 34.8°

This angle is measured with respect to the x-axis (horizontal), but in general the angles in optics are measured from the y-axis so that the angle is

θ = 90 - 34.8

θr = 55.2 °

6 0

3 years ago