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2 years ago

When an object slides,there is less friction than when it rolls

Physics

1 answer:

Butoxors [25]2 years ago

4 0

Answer:

False

Explanation:

Rolling friction takes place when an object rolls on the surface. Sliding friction takes place when two surfaces are rubbed against each other. Rolling friction is much less than sliding friction for same pair of bodies. When one body rolls upon another, there is theoretically no sliding or slip between them.

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Early in the twentieth century, a group of German psychologists noticed that people tend to organize a cluster of sensations int

yan [13]

Answer:

The correct option is D

D) Gestalt

Explanation:

In the earlier 20th century, a group of German scientists named Max Wertheimer, Wolfgang Köhler and Kurt Koffka, noticed that people tend to organzie a cluster of information into a Gestalt.

Gestalt is a German word which means the way things are placed or put together as a whole. In the field of phychology, it can be defined as a pattern or configuration. In this context, it included the human mind and its behavior as a whole.

The Gestalt theory states that:

"The whole of anything is greater than its parts and that attributes of the whole can't be deduced by analyzing any of the parts on their own accord"

5 0

2 years ago

A projectile is launched into the air with an initial speed of 40 m/s and a launch angle of 20° above the horizontal. The projec

miv72 [106K]

Explanation:

V=40m/s

Vy=V.sina=40.sin20=40 . 0.342=13.68m/s

Vx=V.cosa=40.cos20=40 . 0.766=30.64m/s

Projectile travels during 5 seconds and the ramge becomes:

x=V.t=30.64 . 5=153.2m

7 0

2 years ago

1 Write 7 next to the statements that are true.

Grace [21]

Answer: The pressure in a liquid dec reaches with depth. F

The pressure in a liquid increases with depth.

The upthrust on an object is larger when it is deeper in a pool. 7

The bottom of a dam is thinner than the top of a dam. F

The bottom of a dam is thicker than the top of a dam.

The pressure is bigger at the bottom of a lake because of the weight of water above it. 7

I think these are the answers.

7 0

3 years ago

The current theory of the structure of the

Mariana [72]

Answers:

a) $2.82(10)^{21} kg$

b) $1410 J$

c) $36.62 m/s$

Explanation:

<h3>a) Mass of the continent</h3>

Density $\rho$ is defined as a relation between mass $m$ and volume $V$ :

$\rho=\frac{m}{V}$ (1)

Where:

$\rho=2720 kg/m^{3}$ is the average density of the continent

$m$ is the mass of the continent

$V$ is the volume of the continent, which can be estimated is we assume it as a a slab of rock 5300 km on a side and 37 km deep:

$V=(length)(width)(depth)=(5300 km)(5300 km)(37 km)=1,030,330,000 km^{3} \frac{(1000 m)^{3}}{1 km^{3}}=1.03933(10)^{18} m^{3}$

Finding the mass:

$m=\rho V$ (2)

$m=(2720 kg/m^{3})(1.03933(10)^{18} m^{3})$ (3)

$m=2.82(10)^{21} kg$ (4) This is the mass of the continent

<h3>b) Kinetic energy of the continent</h3>

Kinetic energy $K$ is given by the following equation:

$K=\frac{1}{2}mv^{2}$ (5)

Where:

$m=2.82(10)^{21} kg$ is the mass of the continent

$v=4.8 \frac{cm}{year} \frac{1 m}{100 cm} \frac{1 year}{365 days} \frac{1 day}{24 hours} \frac{1 hour}{3600 s}=1(10)^{-9} m/s$ is the velocity of the continent

$K=\frac{1}{2}(2.82(10)^{21} kg)(1(10)^{-9} m/s)^{2}$ (6)

$K=1410 J$ (7) This is the kinetic energy of the continent

<h3>c) Speed of the jogger</h3>

If we have a jogger with mass $m=77 kg$ and the same kinetic energy as that of the continent $1413 J$ , we can find its velocity by isolating $v$ from (5):

$v=\sqrt{\frac{2 K}{m}}$ (6)

$v=\sqrt{\frac{2 (1413 J)}{77 kg}}$

Finally:

$v=36.62 m/s$ This is the speed of the jogger

5 0

3 years ago

Positive ions have blank protons than electrons

grandymaker [24]

Postitive ions have more protons than electrons, because protons are positively charged. Electrons have a negative charge, so if there were less protons than electrons the job would be negative. If there were the same amount of both, then the positive and negative charges balance each other out, making a neutral charge.

5 0

2 years ago