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3 years ago

Where do objects becomes weightless and why?

2 answers:

6 0

Object become weightless in space and in water. gravity is what holds an object down, without gravity object would float around.

Fed [463]3 years ago

5 0

Weight = (mass) x (local acceleration of gravity)

The local acceleration of gravity depends on the other masses
around you and your distance from them. So an object can only be
truly weightless when it's infinitely far away from any other mass.

But an object appears to be weightless when it's in free fall, that is,
when the only force acting on it is the force of gravity. In that situation,
the sensation of 'weight' is impossible ... you can never feel that something
is pressing against you, because everything else is also in free fall.
So a scale on the floor can't exert force against your feet, the mattress
on your bed can't exert force against your back, and your heart, liver,
stomach and spleen can't exert force against your other guts.
Nothing seems to have weight, because everything is falling with
the same acceleration.

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The normal force acting on an object and the force of static friction do zero work on the object. However the reason that the wo

spin [16.1K]

Answer:

<em>The normal force is perpendicular to the displacement</em>

<em>The static friction force produces no displacement</em>

Explanation:

Work Done By Special Forces

The work is a physical magnitude that measures the dot product of the force applied to an object by the displacement it produces in it.

$W=\vec F\ \vec r$

It can be written in its scalar version as

$W=F.d.cos\theta$

Being F and d the magnitudes of the force and displacement, and $\theta$ the angle between them

If the angle is zero, the work is at maximum, it the angle is 90°, the work is zero. If the angle is between 90° and 180°, the work is negative.

The normal force acts in the vertical direction when the object is being pushed horizontally. It means the angle between the force and the displacement is 90°, thus the work is

$W=N.d.cos90^o=0$

The work is zero because the force and the displacement are perpendicular

The static friction force exists only when the object is being applied a force of a magnitude not large enough to produce movement, i.e. the object is at rest. If the object is moved, the friction force is still present, but it's called dynamic friction force, usually smaller than the static.

Since in this case, there is no displacement, d=0, and the work is

$W=F_r(0)cos180^o=0$

3 0

3 years ago

A 55.0-g aluminum block initially at 27.5 degree C absorbs 725 J of heat. What is the final temperature of the aluminum? Express

andrew11 [14]

Answer:

Final temperature of the aluminum = 41.8 °C

Explanation:

We have the equation for energy

E = mcΔT

Here m = 55 g = 0.055 kg

ΔT = T - 27.5

Specific heat capacity of aluminum = 921.096 J/kg.K

E = 725 J

Substituting

E = mcΔT

725 = 0.055 x 921.096 x (T - 27.5)

T - 27.5 = 14.31

T = 41.81 ° C = 41.8 °C

Final temperature of the aluminum = 41.8 °C

6 0

3 years ago

A bag containing 0ºC ice is much more effective in absorbing energy than one containing the same amount of 0ºC water.

rosijanka [135]

Answer:

No temperature change occurs from heat transfer if ice melts and becomes liquid water (i.e., during a phase change). For example, consider water dripping from icicles melting on a roof warmed by the Sun. Conversely, water freezes in an ice tray cooled by lower-temperature surroundings.

Explanation:

Energy is required to melt a solid because the cohesive bonds between the molecules in the solid must be broken apart such that, in the liquid, the molecules can move around at comparable kinetic energies; thus, there is no rise in temperature. Similarly, energy is needed to vaporize a liquid, because molecules in a liquid interact with each other via attractive forces. There is no temperature change until a phase change is complete. The temperature of a cup of soda initially at 0ºC stays at 0ºC until all the ice has melted. Conversely, energy is released during freezing and condensation, usually in the form of thermal energy. Work is done by cohesive forces when molecules are brought together. The corresponding energy must be given off (dissipated) to allow them to stay together Figure 2.

The energy involved in a phase change depends on two major factors: the number and strength of bonds or force pairs. The number of bonds is proportional to the number of molecules and thus to the mass of the sample. The strength of forces depends on the type of molecules. The heat Q required to change the phase of a sample of mass m is given by

Q = mLf (melting/freezing,

Q = mLv (vaporization/condensation),

where the latent heat of fusion, Lf, and latent heat of vaporization, Lv, are material constants that are determined experimentally.

6 0

2 years ago

) In the figure below, three charges K, L and M are placed at the corners of an equilateral triangle. If K and L are fixed, in w

abruzzese [7]

Answer:

Explanation:

Negative (-) charge M will not move towards negative (-) charge K because, same charges will not attract each other in the given case

Negative (-) charge at the M tends to move towards positive (+) charge L in the direction of B) because opposite charges attract each other.

4 0

3 years ago

Plasticity refers to the

olasank [31]

the brain's ability to change throughout the lifespan as a result of experience

5 0

3 years ago