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natima [27]
3 years ago
7

Help me please :(((((((

Physics
2 answers:
Dimas [21]3 years ago
5 0

Answer: A.

Explanation: Roughly 180 - 200 million years ago, just before the first dinosaurs evolved. Mammals themselves evolved from a group or reptiles which exhibited mammal-like traits. One of them was specialized teeth. Reptiles tend to have teeth all the same shape. The mammal-like reptiles evolved tiny teeth in front of the jaw and two pairs of over sized fangs along the the sides. Like modern mammals, the head was large in proportion to the rest of the body. The jaws were also evolving another mammal trait, the ability to move sideways. Despite the lack of specialized teeth, acute hearing and the ability to chew, the dinosaurs evolved an adaptation which made them far more successful than mammals--modified leg bones. These limbs could be articulated directly under their bodies. This enabled the legs to support more weight, since the limbs were now under the body instead of at the sides. Then dinosaurs did something which secured their dominance for the next 120 million years - they began to stand on two legs. Although the back was still parallel to the ground, running on two legs greatly increased the dinosaur's speed. Mammals could simply not compete with swift, giant predators and were forced to remain small, and most became nocturnal to evade dinosaurs which were probably active during the day. Despite that they managed to survive which allowed the further evolution of mammals into us, humans.

sveta [45]3 years ago
5 0

In the Cenozoic period only mammals were alive. All dinosaurs had gone extinct leaving animals such as cave lions, woolly mammoths, and cave bears. Considering that Dinosaurs had gone extinct roughly 66 million years ago in the Cretaceous era and the Cenozoic era was 66 million years ago, the beginning of the Cenozoic era started with the extinction of dinosaurs.

Answer: D

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a square loop whose sides are long is made with copper wire of radius , assuming resistivity of copper is . if a magnetic field
OLEGan [10]

A square loop whose sides are long is made of copper wire of radius , given the resistivity of copper is . if the magnetic field perpendicular to the loop changes at a constant rate of I = 14.029 mA.

The basic characteristic of a substance that measures how effectively it resists an electric current is called electrical resistance. A material with low resistance is a material that easily conducts electric current. A Greek letter is often used to indicate resistivity. Electrical resistance is a basic property of a material that measures how strongly it resists an electric current. The SI unit for electrical resistance is the ohmmeter.

We use magnetic field as a tool to describe how the magnetic field is distributed in the space around and inside something of a magnetic nature. A material with low resistance is a material that easily conducts electric current. A Greek letter is often used to indicate resistivity. An ohmmeter is a unit of electrical resistance in the SI system.

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The complete question is :

A square loop whose sides are 6.0-cm long is made with copper wire of radius 1.0 mm. If a magnetic field perpendicular to the loop is changing at a rate of 5.0 mT/s, what is the current in the loop?

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2 years ago
Canada is the country (dash)of the united States
lana66690 [7]

I believe it is north.

5 0
3 years ago
A cell phone weighing 80 grams is flying through the air at 15 m/s. What is its kinetic energy
Contact [7]

Answer:

The kinetic energy of the cell phone is 9J

Explanation:

The kinetic energy is the energy possessed by a body by virtue of motion.

The kinetic energy is expressed as

KE= 1/2m(v)²

Given data

Mass of cell phone m= 80g--to kg=80/1000= 0.08kg

Velocity of cell phone v= 15m/s

Substituting our given data we have

KE= 1/2*0.08(15)²

KE= (0.08*225)/2

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KE= 9J

8 0
3 years ago
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trapecia [35]
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6 0
4 years ago
Read 2 more answers
I). Mechanical energy is the sum of potential energy and kinetic energy in an object that is used to do work.
Dmitry_Shevchenko [17]

Answer:

false statement : b )  For the motion of a cart on an incline plane having a coefficient of kinetic friction of 0.5, the magnitude of the change in kinetic energy equals the magnitude of the change in gravitational potential energy

Explanation:

mechanical energy = potential energy + kinetic energy = constant

differentiating both side

Δ potential energy + Δ kinetic energy = 0

Δ potential energy = -  Δ kinetic energy

first statement is true.

Friction is a non conservative force so inter-conversion of potential and kinetic energy is not possible in that case. In case of second  option,  the correct relation is as follows

change in gravitational potential energy = change in kinetic energy + work done against friction .

So given 2 nd  option is incorrect.

In case of no change in gravitational energy , work done is equal to

change in kinetic energy.

4 0
3 years ago
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