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2 years ago

Compare and contrast four types of friction

1 answer:

6 0

Some of these frictions depend on the Pressure, temperature of atmosphere.

Static Friction: This is the friction force when two objects in contact are not moving relative to each other. This friction is higher than kinetic friction.

Kinetic or Dynamic friction: this the friction force opposing the motion of objects, when two objects in contact are in motion relative to each other. It is less than the static friction. The two surfaces are rubbing against each other as they move.

Rolling friction: This is the friction when two objects are in contact and one object is rolling over the other - like a wheel on a road. The point of contact appears as stationary. The rolling friction is very less compared to static friction & dynamic friction.

Lubricated friction: this is the friction between two solid surfaces in contact with a layer of lubricant fluid flowing in between them. This friction is the least.

Fluid friction - viscosity : this is friction between two adjacent layers that are moving relative to each other at different speeds in a fluid. This is not high.

Internal friction: when an object is compressed and forced to deform, like in a piece of rubber, there is friction between the layers, that opposes this deformation.

Skin friction is the friction that opposes movement of a fluid across a solid surface. This is also called drag. When a coin is dropped in water, there is a friction called drag on the coin. Same is the case when a ball is thrown, a drag is experienced by the ball due to the drag of air.

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A lizard accelerates from 2 m/s to 10 m/s in 4 seconds. what is the lizard average acceleration

VLD [36.1K]

Acceleration = (change in speed) / (time for the change)

change in speed = (ending speed) - (starting speed)

change in speed = (10 m/s) - (2 m/s) = 8 m/s

Acceleration = (8 m/s) / (4 sec)

Acceleration = (8/4) (m/s²)

<em>Acceleration = 2 m/s²</em>

8 0

2 years ago

It is 5.00 km from your home to the physics lab. As part of your physical fitness program, you could run that distance at 10.0 k

8_murik_8 [283]

Answer:

a. Walking burns up more energy.

b. 1740 kJ

c. This is because more intense exercise releases a lot of energy in a short period of time, whereas, less intense energy releases it energy gradually over a long period of time.

Explanation:

a. We know energy W = Pt where P = power and t = time.

Now for walking, t = d/v where d = distance = 5.00 km and v = speed = 3.00 km/hr and P = 290 W

So, t = d/v = 5.00 km/3.00 km/hr = 5/3 hr = 5/3 × 3600 s = 6000 s

W = Pt = 290 W × 6000 s = 1740000 = 1740 kJ

Now for running, t = d/v where d = distance = 5.00 km and v = speed = 10.00 km/hr

So, t = d/v = 5.00 km/10.00 km/hr = 0.5 hr = 0.5 × 3600 s = 1800 s and P = 700 W

W = Pt = 700 W × 1800 s = 1260000 = 1260 kJ

Since walking burns up 1740 kJ and running burns up 1260 kJ, walking burns up more energy.

b. It burns up 1740 kJ

c. This is because more intense exercise releases a lot of energy in a short period of time, whereas, less intense energy releases it energy gradually over a long period of time.

4 0

2 years ago

In a science fiction story, a microscopic black hole is given an enormous positive charge by firing an un-neutralized ion drive

Olegator [25]

Answer: distance d = 4.73e10m

Explanation: Suppose the charge on the black hole is 5740 C which is a positive charge.

Using electric potential V formula:

V = kq / d

Where K = 9.05×10^9Nm^2/C

And e = 1.6×10^-19C

But you don't need to substitute it.

1090 V = 8.99e9N·m²/C² * 5740C /d

Make d the subject of formula

d = 4.73e10 m

6 0

2 years ago

Over 4 seconds, a car's momentum decreases by 1000 kg m/s how much force did it take to make this happen?

kotykmax [81]

Answer:

250N

Explanation:

Given parameters:

Time = 4s

Momentum = 1000kgm/s

Unknown:

Force = ?

Solution:

To solve this problem, we use Newton's second law of motion;

Ft = Momentum

F is the force

t is the time

So;

F x 4 = 1000kgm/s

F = 250N

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2 years ago

Change.

solniwko [45]

Option E, Fiat money includes currency, checking deposits and credit cards .

<u>Explanation: </u>

Fiat money has been the currency issued by the government which is not sponsored by actual resources like gold or silver, but by the country that approved it.

Instead of the price of a product, the valuation of fiat money is extracted from the connection between production and consumption and stability of the authorizing state. Fiat currencies, including that of the U.S. dollar, euro, and other major international currencies seem to be the most common paper currencies.

One risk for fiat money is to print too many of those by regimes that contribute to hyperinflation.

Fiat money is government-supported monetary money and is treated as a legal tender. The capital is provided by physical goods such as valuable metals or instruments including checks and credit cards. The world currencies, backed by gold, were symbolic until 1971.

7 0

2 years ago