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3 years ago

8

To pull a nail out of a wood board a carpenter does 1000 J of work. The hammer he uses does 835 J of work. What is the efficienc

y of the hammer?

1 answer:

saw5 [17]3 years ago

7 0

Answer:

83.5%

Explanation:

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Refer back to your data. List all indicators of chemical change that you observed.

Xelga [282]

Below are the 5 main indicators of chemical change.

Chemical change indicators:<span>
Color change
</span>Temperature change
Precipitate formation<span>
Odor
Bubble formation

I hope this helps!</span>

3 0

3 years ago

Read 2 more answers

The speed of a moving bullet can be deter-

Bad White [126]

Answer:

<em>v = 381 m/s</em>

Explanation:

<u>Linear Speed</u>

The linear speed of the bullet is calculated by the formula:

$\displaystyle v=\frac{x}{t}$

Where:

x = Distance traveled

t = Time needed to travel x

We are given the distance the bullet travels x=61 cm = 0.61 m. We need to determine the time the bullet took to make the holes between the two disks.

The formula for the angular speed of a rotating object is:

$\displaystyle \omega=\frac{\theta}{t}$

Where θ is the angular displacement and t is the time. Solving for t:

$\displaystyle t=\frac{\theta}{\omega}$

The angular displacement is θ=14°. Converting to radians:

$\theta=14*\pi/180=0.2443\ rad$

The angular speed is w=1436 rev/min. Converting to rad/s:

$\omega = 1436*2\pi/60=150.3776\ rad/s$

Thus the time is:

$\displaystyle t=\frac{0.2443\ rad}{150.3776\ rad/s}$

t = 0.0016 s

Thus the speed of the bullet is:

$\displaystyle v=\frac{0.61}{0.0016}$

v = 381 m/s

7 0

3 years ago

A calorimeter is used to determine the specific heat capacity of a test metal. If the specific heat capacity of water is known,

denis23 [38]

Answer:

initial and final temperatures of both the water and metal, mass of the metal, and mass of the water

Explanation:

Heat lost by the metal, $Q = mc(t_{2} - t_{1})$

Heat gained by the water in the calorimeter, $Q_{w} = m_{w}c_{w}(t_{2w} - t_{1w})$

For energy to be conserved in the system, the heat lost by the metal will equal the heat gain by the water in the calorimeter.

$mc(t_{2} - t_{1}) = m_{w}c_{w}(t_{2w} - t_{1w})$

Where,

m is the mass of the metal

c is specific heat capacity of the metal

t₂ is the final temperature of the metal

t₁ is the initial temperature of the metal

$m_{w}$ is the mass of the water

$c_{w}$ is specific heat capacity of water

$t_{2w}$ is the final temperature of water

$t_{1w}$ is the initial temperature of water

From the question given, specific heat capacity of the water is known, the quantities to be measured are;

Initial and final temperatures of both the water and metal,

Mass of the metal, and mass of the water

8 0

3 years ago

The diagram shows movement of thermal energy. At bottom a fire has red curved lines labeled Y with arrowheads pointing upward to

Pepsi [2]

Answer:

X and Z

Explanation:

Conduction occurs through direct physical contact. Heat transferred from the pot to the handle, and from the handle to the hand, are both examples of conduction.

6 0

3 years ago

Read 2 more answers

In a certain time period a coil of wire is rotated from one orientation to another with respect to a uniform 0.38-T magnetic fie

Evgesh-ka [11]

Answer:

8.4 V

Explanation:

induced emf, e1 = 5.8 V

Magnetic field, B1 = 0.38 T

magnetic field, B2 = 0.55 T

induced emf, e2 = ?

As we know that the induced emf is directly proportional to the magnetic field strength.

When the other parameters remains constant then

$\frac{e_{1}}{e_{2}}=\frac{B_{1}}{B_{2}}$

$\frac{5.8}{e_{2}}=\frac{0.38}{0.55}$

e2 = 8.4 V

Thus, the induced emf is 8.4 V.

4 0

3 years ago