Which of the following is a disadvantage of friction?Air resistance of a parachute slows down the descent of a skydiver.
Friction reduces the efficiency of engines and other machines by converting parts of their kinetic energy into heat.
Friction makes it possible for you to grasp items with your hand.
Friction enables you to walk.
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Explanation:
The disadvantage of friction is that it reduces the efficiency of engines and other machines by converting parts of their kinetic energy into heat.
Friction between moving parts in engines and machines causes resistance, leading to energy loss through heat generation. This energy loss affects the overall efficiency of the system and can lead to increased wear and tear on the components. Engineers often design systems to minimize frictional losses through the use of lubricants, materials with low friction coefficients, or implementing other techniques to reduce friction.
The other statements mention advantages of friction:
- Air resistance of a parachute slows down the descent of a skydiver, which is beneficial for a controlled landing.
- Friction enables you to grasp items with your hand, providing the necessary grip and control.
- Friction also enables you to walk by creating the necessary traction between your feet and the ground, allowing forward motion.
Related Questions
In the equation for Ohm’s law what does I stand for?A. current B. resistance C. kilowatts D. voltage
The force that moving, charged particles exert on one another is called
a car is moving with a constant speed of 20 meters per second.What total distance does the car travel in 2 minutes
Which state of matter has the greatest amount of kinetic energy?
b) down
c) right
d) left
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Answers
Answer:
3.43 kPa
Explanation:
Pressure is defined as the ratio between the force applied and the area of the surface on which the force is applied:
in this problem, the force corresponds to the weight of the load, which is given by the product between its mass (350 kg) and the acceleration due to gravity (9.8 m/s^2):
And since the area on which this force is applied is , the pressure exerted on the upper surface of the liquid is
I assume that 350kg is the mass
Therefore,
350 x 9.8 (gravity) = 3430N
3430 / 1 = 3430Pa
3.43 KPa
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when you toss it.
You give the ball kinetic energy. As it goes up, the kinetic energy
changes to potential energy, and on the way down, that potential
energy changes back into kinetic energy.
If there's nothing along the way to steal any energy from the ball,
then its TOTAL energy (kinetic PLUS potential) is constant all the
way up and down.
But in this question, there IS something else in the picture, and it
steals energy from the ball. Air resistance is partly the friction of
the air molecules scraping against the ball, and partly the work
that the ball has to do in order to push air out of the way so that
it can get through. All of that steals energy whenever the ball is
moving.
So figure it out: If you give it some energy when you throw it,
and it can never have any more than that because it doesn't
have little jet engines on it, and the air is constantly robbing
some of the energy whenever the ball is moving, then the most
it can ever have is just as it leaves your hand.
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There are two ways to do this one.
In due consideration of 5 points, I have decided
to do it the easy way.
Kinetic energy = (1/2) (mass) (speed²)
The car's KE at the slower speed = (1/2 mass) x (10²)
= 75,000 joules .
The car's KE at the faster speed = (1/2 mass) x (20²)
= 300,000 joules .
The difference in kinetic energy between
the slower and faster speeds =
(300,000 - 75,000) = 225,000 joules.
THAT's the work that had to be done in order to accelerate
the car to double the original speed.
Answers
Answer:
S = t^3 - 9 t^2 + 18 position of particle
V = dS / dt = 3 t^2 - 18 t speed of particle at time t
V = 3 * 4^2 - 18 * 4 = 48 - 72 = - 24 ft/sec