1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Archy [21]
2 years ago
11

Efficiency of a machine is always less than 100% why?

Physics
1 answer:
kifflom [539]2 years ago
7 0

The reason the efficiency is always less than 100% is because there is always some sort of friction in the machine.


Answer: because of friction

You might be interested in
A cord is used to vertically lower an initially stationary block of mass M = 3.6 kg at a constant downward acceleration of g/7.
dalvyx [7]

Answer:

(a) W_c=127.008 J

(b) W_g=148.176 J

(c) K.E. = 21.168 J

(d) v=3.4293m.s^{-1}

Explanation:

Given:

  • mass of a block, M = 3.6 kg
  • initial velocity of the block, u=0 m.s^{-1}
  • constant downward acceleration, a_d= \frac{g}{7}

\Rightarrow That a constant upward acceleration of \frac{6g}{7} is applied in the presence of gravity.

∴a=- \frac{6g}{7}

  • height through which the block falls, d = 4.2 m

(a)

Force by the cord on the block,

F_c= M\times a

F_c=3.6\times (-6)\times\frac{9.8}{7}

F_c=-30.24 N

∴Work by the cord on the block,

W_c= F_c\times d

W_c= -30.24\times 4.2

We take -ve sign because the direction of force and the displacement are opposite to each other.

W_c=-127.008 J

(b)

Force on the block due to gravity:

F_g= M.g

∵the gravity is naturally a constant and we cannot change it

F_g=3.6\times 9.8

F_g=35.28 N

∴Work by the gravity on the block,

W_g=F_g\times d

W_g=35.28\times 4.2

W_g=148.176 J

(c)

Kinetic energy of the block will be equal to the net work done i.e. sum of the two works.

mathematically:

K.E.= W_g+W_c

K.E.=148.176-127.008

K.E. = 21.168 J

(d)

From the equation of motion:

v^2=u^2+2a_d\times d

putting the respective values:

v=\sqrt{0^2+2\times \frac{9.8}{7}\times 4.2 }

v=3.4293m.s^{-1} is the speed when the block has fallen 4.2 meters.

6 0
3 years ago
Which group of measurements is the most precise? A) 2 g, 3 g, 4 g B) 2 g, 2.5 g, 3 g C) 2.0 g, 3.0 g, 4.0 g, 5.0 g D) 2.0 g, 3.0
siniylev [52]
The answer to your question is A
3 0
3 years ago
Which statement explains the similarity between momentum and kinetic energy of an object?
Anon25 [30]

Answer:B.

Both increase as the mass and velocity increase.

3 0
3 years ago
Read 2 more answers
A CD player uses 1200 J of energy in 60 seconds what is the power rating of the CD player
tiny-mole [99]

The power equals energy divided by the time

P=E/t

P=1200/60

P=20W

Hope you get it!

8 0
3 years ago
If someone ways 600 newtons and the shoes have an area of 300cm squared, what pressure does he exert on the ground?
lukranit [14]
Pressure = Force / Area

Put your data in front of yourself.

Force = 600 Newtons
Area = 300 cm^2

Firstly you need to convert the area into m^2 and you do this by diving 300 with 10000.

Now you use the formula:-
Pressure = 600/ 0.03
Which comes out to be 20,000 Pa.

Hope this helps!
4 0
3 years ago
Other questions:
  • A circuit has a current of 1.2 A. If the voltage decreases to one-third of its original amount while the resistance remains cons
    8·1 answer
  • On Mars a rock falls an unknown vertical distance from a resting position and lands in a crater. If it takes the rock 2.5 second
    15·1 answer
  • Explain why squeezing a plastic mustard bottle forces mustard out to top.
    10·2 answers
  • if we could build rockets that could travel at the speed of light, how many years would it take for an astronaut to travel from
    13·1 answer
  • A rod of length L has a charge Q uniformly distributed along its length. The rod lies along the y axis with one end at the origi
    10·1 answer
  • Identity the kinds of force in the following activities<br> A lemon falls from the tree to ground
    14·2 answers
  • A person is riding on a Ferris wheel of radius R. He starts at the lowest point of the wheel. When the wheel makes one complete
    6·1 answer
  • State one of Kepler's laws of gravitation
    12·2 answers
  • A 75kg hockey player is skating across the ice at a speed of 6.0m/s. What is the magnitude of the average force required to stop
    9·1 answer
  • The diagram below show the alignment of the sun moon and earth
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!