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3 years ago

Which of the following is a false statement? Select one:

Physics

1 answer:

Art [367]3 years ago

6 0

Answer:

The false statement is in option 'd': The center of mass of an object must lie within the object.

Explanation:

Center of mass is a theoretical point in a system of particles where the whole mass of the system is assumed to be concentrated.

Mathematically the position vector of center of mass is defined as

$\overrightarrow{r}_{com}=\int \overrightarrow{r}_{i}dm$

where,

$\overrightarrow{r}_{i}$ is the position vector of the mass dm.

As we can see for homogenous symmetrical objects such as a sphere,cube,disc the center of mass is located at the centroid of the shapes itself but in many shapes it is located outside the body also.

Examples of shapes in which center of mass is located outside the body:

1) Horseshoe shaped body.

2) A thin ring.

In many cases we can make shapes of bodies whose center of mass lies outside the body.

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A simple electric motor consists of a 220-turn coil, 4.4 cm in diameter, mounted between the poles of a magnet that produces a 9

Verdich [7]

Answer:

$M = 5.01\ A.m^2$

Explanation:

It is given that,

Number of turns in the coil, N = 220

Diameter of the coil, d = 4.4 cm

Radius of the coil, r = 2.2 cm = 0.022 m

Magnetic field produced by the poles of magnet, $B=96\ mT=96\times 10^{-3}\ T$

Current flowing in the coil, I = 15 A

Let M is the coil's magnetic dipole moment. Its formula is given by :

$M=N\times I\times A$

$M=220\times 15\times \pi (0.022)^2$

$M = 5.01\ A.m^2$

So, the coil's magnetic dipole moment is $5.01\ A.m^2$ . Hence, this is the required solution.

4 0

3 years ago

A skydiver jumps out of a hovering helicopter. A few seconds later, another diver jumps out, so they both fall along the same ve

Sergio039 [100]

Answer:

distance difference would a) increase

speed difference would f) stay the same

Explanation:

Let t be the time the 2nd skydiver takes to travel, since the first skydiver jumped first, his time would be t + Δt where Δt represent the duration between the the first skydiver and the 2nd one. Remember that as t progress (increases), Δt remain constant.

Their equations of motion for distance and velocities are

$s_2 = gt^2/2$

$s_1 = g(t + \Delta t)^2/2$

$v_2 = gt$

$v_1 = g(t + \Delta t)$

Their difference in distance are therefore:

$\Delta s = s_1 - s_2 = g(t + \Delta t)^2/2 - gt^2/2$

$\Delta s = g/2((t + \Delta t)^2 - t^2)$

$\Delta s = g/2(t + \Delta t - t)(t + \Delta t + t)$ (As $A^2 - B^2 = (A-B)(A+B)$

$\Delta s = g\Delta t/2(2t + \Delta t)$

So as time progress t increases, Δs would also increases, their distance becomes wider with time.

Similarly for their velocity difference

$\Delta v = v_1 - v_2 = g(t + \Delta t) - gt$

$\Delta v = gt + g\Delta t - gt = g\Delta t$

Since g and Δt both are constant, Δv would also remain constant, their difference in velocity remain the same.

This of this in this way: only the DIFFERENCE in speed stay the same, their own individual speed increases at same rate (due to same acceleration g). But the first skydiver is already at a faster speed (because he jumped first) when the 2nd one jumps. The 1st one would travel more distance compare to the 2nd one in a unit of time.

8 0

3 years ago

Read 2 more answers

What do zooplankton and krill have in common?

serious [3.7K]

<h2><em>Hello, thank you for choosing brainly today. My name is Ethan and I'll be solving your question. </em><em><u>"What do zooplankton and krill have in common?"</u></em></h2>

Krill and plankton are two groups of organisms found in the ocean. Krill are species of crustacean related to shrimp, and serve as a very important link in the food chain of the sea. Plankton consist of a larger group of organisms with much more variety, including bacteria, algae, protozoans, jellyfish and some species of cephalopods.

Propulsion

The primary factor that determines whether a species is plankton or not is propulsion. Plankton organisms lack the ability to swim against the tide, and instead float from place to place on sea currents. They may be capable of some movement, and some types of plankton can even hunt for food, but none is powerful enough to make its own headway through the ocean. Adult krill are capable of swimming against currents, but their larvae and eggs fall into the plankton category.

Variation

Krill are crustaceans of the Euphausiacea order, which consists of 86 different species. Plankton, on the other hand, can come from a wide variety of different species and orders. Plankton fall into three broad categories, depending on their primary function. Phytoplankton are plant-like organisms, capable of photosynthesis. Zooplankton are animal plankton species that get their nutrients by eating other microscopic organisms. Bacterioplankton are the smallest plankton, and often serve as food for zooplankton and other lifeforms.

Appearance

Krill species have similar characteristics and generally resemble tiny shrimp. Most species reach around 2 centimeters (0.8 inches) as adults, while the largest species can reach sizes of up to 15 centimeters (5.9 inches). Plankton, on the other hand, consists of organisms of many different shapes and sizes. The smallest categories include microscopic viruses, protozoans, small crustaceans, and other tiny organisms. At the larger end of the scale, megaplankton are any plankton over 2 centimeters (0.8 inches) in size, and include large animals, such as cephalopods and jellyfish. The largest plankton is the lion's mane jellyfish, which can reach 2.5 meters (8.2 feet) in diameter and grow tentacles more than 36.5 meters (120 feet) long.

Role

Plankton and krill serve similar, but slightly different, roles in the food chain. Phytoplankton synthesize nutrients, while bacterioplankton recycle nutrients from decomposing matter in the ocean, providing some of the fundamental sources of nutrition for all ocean creatures. Zooplankton serve to concentrate those nutrients by eating smaller plankton and serving as food for larger creatures. Krill are one step up in the food chain, eating plankton and serving as a nutrient bridge from microscopic life forms to larger fish and mammals.

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3 years ago

Properties of most medals include

Aleonysh [2.5K]

Answer:

Metals are lustrous, malleable, ductile, good conductors of heat and electricity. Other properties include: State: Metals are solids at room temperature with the exception of mercury, which is liquid at room temperature (Gallium is liquid on hot days).

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3 years ago

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nika2105 [10]

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