What is the wavelength of an earthquake wave if it has a speed of 9 km/s and a frequency of 2 Hz?

The objective lens in a DVD player must move quickly to keep the laser beam focused on the disc's reflective layer. Why must thi

Zinaida [17]

Explanation:

The small mass of lens in a DVD player accounts for small inertia of the lens. Hence, even on application of force of small magnitude, the lens is rapidly accelerated. Moreover, the small mass of lens also accounts for lower resistance to change in its motion and therefore, again can be rapidly accelerated back and forth.

4 0

2 years ago

A 6.50-g sample of copper metal at 25.0°C is heated by the addition of 84.0 J of energy. The final temperature of the copper is

Mekhanik [1.2K]

Answer:

Final temperature of the copper is 59 degrees Celsius

Explanation:

It is given that,

Mass of the sample of copper metal, m = 6.5 g

Initial temperature of the metal, $T_i=25^{\circ}\ C=298\ K$

Heat generated, Q = 84 J

The specific heat capacity of liquid water is 0.38 J/g-K

Let $T_f$ is the final temperature of the copper. It can be calculated using the definition of specific heat of any substance. It is given by :

$Q=mc\Delta T$

$Q=mc(T_f-T_i)$

$T_f=\dfrac{Q}{mc}+T_i$

$T_f=\dfrac{84}{6.5\times 0.38}+298$

$T_f=332\ K$

or

$T_f=59^{\circ}C$

So, the final temperature of the copper is 59 degrees Celsius. Hence, this is the required solution.

4 0

2 years ago

A solution is prepared by dissolving 98.6 g of nacl in enough water to form 875 ml of solution. calculate the mass % of the solu

Crank

I'm guessing 10.6% based on the following information:

Mass soln = density×volume=1.06×875=927.5g
MNaCl/Msoln×100=%M
which means this:

%M=98.6927.5×100=10.6

Was this helpful? I hope so.

7 0

3 years ago

Given the following data, solve for momentum, P=mv

Ratling [72]

Answer:

1000

1200

2.4

10.8

100

4.2

6

24000000

0.75

7 0

1 year ago

What is the effective resistance between the points A and D? A) 1.3 Ω B) 2.2 Ω C) 10 Ω D) 12 Ω

Rudiy27

Answer:

B) 2.2 Ω

Explanation:

First of all, we should notice that the resistor placed between A and B is short-circuited. In fact, the current from point A will follow the wire above between A and C (which has zero resistance), so we can basically ignore the presence of the resistor between A and B, since it has no effect on the circuit.

Then, we can notice that the two resistors between CB and CD are in parallel to each other; therefore, their equivalent resistance is given by:

$\frac{1}{R}=\frac{1}{R_{BC}}+\frac{1}{R_{CD}}=\frac{1}{4.0 \Omega}+\frac{1}{5.0 \Omega}=\frac{9}{20 \Omega}\\R= \frac{20 \Omega}{9}=2.2 \Omega$

6 0

3 years ago