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3 years ago

You do 1,500j of work in using a hammer. the hammer does 825j of work on a nail. what is the efficiency of the hammer?

1 answer:

6 0

A tool or machine's work efficiency is represented by the ratio of the amount of energy exerted and the amount of work done by the object. Thus, if you exert 1500 J work and the hammer does 825 J, the work efficiency is

$Efficiency = \frac{825}{1500} = 0.55$
$Efficiency = 55%$

Thus, the efficiency of the hammer is 55%.

Answer: 55%

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After the collapse of a nebular cloud, atoms begin gravitating together to form a condensed center. What happens next in the sta

ELEN [110]

Well, first of all, I don't think "After the collapse of a nebular cloud ..."
is the first time that "atoms begin gravitating together". Seems to me like
that's what was going on all the time, and it's what caused the nebular cloud
to collapse in the first place.

In any case, once the pressure and temperature at the center get high enough,
you get "ignition" of nuclear fusion, and that's when you first have a "star".

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3 years ago

Read 2 more answers

A student makes a short electromagnet by winding 300 turns of wire around a wooden cylinder of diameter d 5.0 cm. The coil is co

kupik [55]

Answer:

A) μ = A.m²

B) z = 0.46m

Explanation:

A) Magnetic dipole moment of a coil is given by; μ = NIA

Where;

N is number of turns of coil

I is current in wire

A is area

We are given

N = 300 turns; I = 4A ; d =5cm = 0.05m

Area = πd²/4 = π(0.05)²/4 = 0.001963

So,

μ = 300 x 4 x 0.001963 = 2.36 A.m².

B) The magnetic field at a distance z along the coils perpendicular central axis is parallel to the axis and is given by;

B = (μ_o•μ)/(2π•z³)

Let's make z the subject ;

z = [(μ_o•μ)/(2π•B)] ^(⅓)

Where u_o is vacuum permiability with a value of 4π x 10^(-7) H

Also, B = 5 mT = 5 x 10^(-6) T

Thus,

z = [ (4π x 10^(-7)•2.36)/(2π•5 x 10^(-6))]^(⅓)

Solving this gives; z = 0.46m =

3 0

3 years ago

Your heart has four valves. Normally, these valves open to let blood flow through your heart, and then shut to keep it from flow

stiv31 [10]

Answer:

It influences blood flow

7 0

3 years ago

A point charge Q moves on the x-axis in the positive direction with a speed of A point P is on the y-axis at The magnetic field

oee [108]

Answer: q = -52.5 μC

Explanation:

The complete question is given thus;

A point charge Q moves on the x-axis in the positive direction with a speed of 280 m/s. A point P is on the y-axis at y=+70mm. The magnetic field produced at the point P, as the charge moves through the origin, is equal to -0.30uTk. What is the charge Q? (uo=4pi x 10^-7 T m/A).

SOLVING:

from the given parameters we can solve this problem.

Given that the

Speed = 280 m/s

y = 70mm

B = -30 * 10⁻⁶T

Using the equation for magnetic field we have;

Β = μqv*r / 4πr²

making q (charge) the subject of formula we have that;

q = B * 4 *πr² / μqv*r

substituting the values gives us

q = (-0.3*10⁻⁶Tk * 4π * 0.07²) / (4π*10⁻⁷ * 280 ) = - [14.7 * 10⁻¹⁰k / 2.8 * 10⁻⁵ k ]

q = -52.5 μC

cheers i hope this helped !!!

3 0

3 years ago

1. Which statement about friction is true?(1 point) A. Static friction and kinetic friction in a system always act in the same d

ArbitrLikvidat [17]

Answer:

true 1Ay 2D

Explanation:

1) In this exercise you are asked to investigate which statements are true

A) True. The friction force opposes the movement caused by the external force,

B) False. Mantuano in the opposite direction force

C) False. The static and scientific friction force act in the same direction, since the second appears when the movement does not start and the static friction decreases.

D) Fale the static and kinetic friction forces act in the same direction

2) How to overcome friction on a ramp

A) False. If the texture of the surface becomes rough, the friction force increases

B) False. Pressing the brick against the surface increases the normal and as the friction is proportional to the normal, it also increases

C) False. By lowering the table the weight component in the friction direction decreases

D) True. When lifting the board, the weight component increases and therefore can become greater than the friction

Wx-fr = ma

W sin tea - my mg cos tea = m a

As it increases, the sine increases and the cosine decreases.

3 0

3 years ago