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3 years ago

Which statements describe a situation in which work is being done? Check all that apply.

Physics

2 answers:

slava [35]3 years ago

5 0

The work is being done in following cases:

A mover carries a box up a flight of stairs.

A mover carries a box across a room.

Wind blows a pool chair across the yard.

A weightlifter lifts a barbell off the ground.

These are the only cases in which work is being done. The Formula of Work is:

Work= Force applied x Distance moved.

In all of these cases force is being applied and the object on which the force is being applied move in a horizontal or Vertical direction. Thus Work is done !

DanielleElmas [232]3 years ago

5 0

Answer:

A. A box is carried up a flight of stairs by a mover.

D. Wind blows a pool chair across the yard.

E. A weightlifter lifts a barbell off the ground.

Explanation:

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Joaquin mows the lawn at his grandmother’s home during the summer months. Joaquin measured the

nordsb [41]

Velocity is define as how fast an object is moving, and in what direction, it is a vector quantity, meaning velocity has both magnitude and direction. Anything goes to the left is negative, and anything goes to the right is positive.

a. Direction from east to west, given distance 11.5 meters, and time of 7.10 s

V = displacement/time V = -11.5/7.10 S V = -1.62 m/s (going left)

b. Joaquin reaches his original position. Displacement is now zero.

Velocity of the lawnmower is equal to "zero" but if we calculate for the average speed of the lawn, you just have to add the distance covered and the time it take to go back at the original position or point of origin

7 0

3 years ago

Carbon dioxide in a piston-‐‐cylinder is expanded in a polytropic manner. The initialtemperature and pressure are 400 K and 550

Arisa [49]

Answer:

q_poly = 14.55 KJ/kg

Explanation:

Given:

Initial State:

P_i = 550 KPa

T_i = 400 K

Final State:

T_f = 350 K

Constants:

R = 0.189 KJ/kgK

k = 1.289 = c_p / c_v

n = 1.2 (poly-tropic index)

Find:

Determine the heat transfer per kg in the process.

Solution:

-The heat transfer per kg of poly-tropic process is given by the expression:

q_poly = w_poly*(k - n)/(k-1)

- Evaluate w_poly:

w_poly = R*(T_f - T_i)/(1-n)

w_poly = 0.189*(350 - 400)/(1-1.2)

w_poly = 47.25 KJ/kg

-Hence,

q_poly = 47.25*(1.289 - 1.2)/(1.289-1)

q_poly = 14.55 KJ/kg

4 0

3 years ago

Evidence that the cosmic background radiation really is the remnant of a Big Bang comes from predicting characteristics of remna

mario62 [17]

Answer:

B) The cosmic background radiation is expected to contain spectral lines of hydrogen and helium, and it does.

Explanation:

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3 years ago

The Cosmological Argument for the existence of God intellectually follows cause-and-effect back in time -- in effect asking "Whe

ankoles [38]

Answer:

First uncaused cause

Explanation:

Aristotle states that an infinite regression in the principle of causality is not possible. If the regression were infinite, then there would never be a first cause (mover), since this would need another mover to start its motion. Therefore, according to Aristotle, there must be an unmoved mover that moves other things, but is not itself moved by any prior action,

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3 years ago

What determines an object’s thermal energy

Tems11 [23]

Answer:

temperature and mass

Explanation:

The higher the temperature of a given quantity of a substance, more is its thermal energy.

If a substance contains more mass, this also implies that the object has more particles in it . hence, it has high thermal energy.

Additional Information :

Temperature is a measure of the average kinetic energy of the particles of a substance.

The thermal energy of an object depends on three factors:

number of molecules in the object
temperature of the object.
thermal energy it has.

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3 years ago