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sergeinik [125]
4 years ago
7

A geologist is observing the side of a mountain for evidence of erosion when a large rock begins to accelerate down the mountain

side. Using his knowledge of the laws of physics, what change should he conclude caused the rock to accelerate?
A. When stationary the force of gravity on the rock was less, and when accelerating it was greater.

B. When stationary there were no forces on the rock and when accelerating there were forces on it.

C. When stationary there were equal forces on the top and bottom of the rock, but not on the left and right sides.

D. When stationary the rock did not have a net force on it, and when accelerating it did.
Physics
1 answer:
umka2103 [35]4 years ago
8 0
I think it's A.<span>When stationary the force of gravity on the rock was less, and when accelerating it was greater. The rock was in place, gravity was simply making it stay on Earths surface, for the time being, until something unbalanced it</span>
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sp2606 [1]

Answer:it will continue in its state of rest.

Explanation:

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3 years ago
A sports car engine delivers 150 kW to the driveshaft with a thermal efficiency of 20%. The fuel has a heating value of 35 000 k
Andreyy89

Answer:600 kW

Explanation:

Given

Power delivered P=150 kW

Fuel heating value q=35,000 kJ/kg

thermal Efficiency \eta =\frac{Power}{Heat}

0.2=\frac{150}{35,000\times \dot{m}}

where, \dot{m} =mass\ flow\ rate\ of\ fuel

\dot{m}=\frac{150}{35,000\times 0.2}

\dot{m}=0.0214 kg/s

For an Engine

q\dot{m}=P+Q_r , where Q_r=heat\ rejected

Q_r=q\dot{m}-P

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3 0
3 years ago
A magnetic field of 0.276 T exists in the region enclosed by a solenoid that has 517 turns and a diameter of 10.5 cm. Within wha
Advocard [28]

Answer:

The period the field must be reduced to zero is 9.81 x 10⁻⁵ s

Explanation:

Given;

initial value of the magnetic field, B₁ = 0.276 T

number of turns of the solenoid, N = 517 turns

diameter of the solenoid, d = 10.5 cm = 0.105 m

induced emf, = 12.6 kV = 12,600 V

when the field becomes zero, then the final magnetic field value, B₂ = 0

The induced emf is given by Faraday's law;

emf = -\frac{NA\Delta B}{t} \\\\emf = -\frac{NA (B_2 -B_1)}{t} \\\\t = -\frac{NA (B_2 -B_1)}{emf}\\\\t = \frac{NA (B_1 -B_2)}{emf}\\\\where;\\\\t \ is \ the \ time \ when \ B = 0 \ \ (i.e\ B_2 = 0)\\\\A \ is \ the \ area \ of \ the \ coil\\\\A = \frac{\pi d^2}{4} = \frac{\pi (0.105)^2}{4} = 0.00866 \ m^2\\\\t= \frac{(517) \times (0.00866)\times  (0.276 -0)}{12,600}\\\\t = 9.81 \times 10^{-5} \ s

Therefore, the period the field must be reduced to zero is 9.81 x 10⁻⁵ s

4 0
4 years ago
Write down the role played by four digestive juices in digestion and the
valentinak56 [21]

Answer:

Digestive juices secreted by various organs such as salivary glands in the mouth, stomach, liver and pancreas help in the process of digestion of food. Saliva secreted by the salivary glands in the mouth aids in the breakdown of starch present in the food to simple sugar

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3 0
3 years ago
The acceleration due to gravity on or near the surface of Earth is 32 ft./s/s. Neglecting friction, from what height must a ston
svetoff [14.1K]

Given :

The acceleration due to gravity on or near the surface of Earth is 32 ft/s/s

To Find :

From what height must a stone be dropped on Earth to strike the ground with a velocity of 136 ft/s.

Solution :

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Therefore, height from which stone is thrown is 289 ft.

3 0
3 years ago
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