Need help asap pls

Based on The MOHS hardness Scale, which mineral could be scratched by a penny but not by a fingernail

melomori [17]

The correct answer is B. Calcite

Explanation:

Mohs hardness scale indicates the hardness of minerals using a scale from 1 to 10 as well as defining the objects or tools that can be used to scratch the minerals. These two features of minerals are shown in the table of the image. About this, it is shown gypsum and talc can be scratched by just a fingernail, considering minerals with a hardness of 2.5 or below can be scratched by a fingernail. In the case of calcite that has a hardness of 3, this cannot be scratched by a fingernail, but it can be scratched by a penny, which works for minerals with a hardness of 3.5 or below. Thus, the correct answer is Calcite.

6 0

3 years ago

A train at rest emits a sound at a frequency of 1057 Hz. An observer in a car travels away from the sound source at a speed of 2

il63 [147K]

Answer:

993.52 Hz

Explanation:

The frequency of sound emitted by the stationery train is 1057 Hz.

The car travels away from the train at 20.6 m/s.

The frequency the observer hears is given by the formula:

$f_o = \frac{v - v_o}{v}f$

where v = velocity of sound = 343 m/s

vo = velocity of observer

f = frequency from source

This phenomenon is known as Doppler's effect.

Therefore:

$f_o = \frac{343 - 20.6}{343} * 1057\\ \\f_o = 322.4 / 343 * 1057\\\\f_o = 993.52 Hz$

The frequency heard by the observer is 993.52 Hz.

4 0

4 years ago

One mole of an ideal gas does 3000 J of work on its surroundings as it expands isothermally to a final pressure of 1.00 atm and

taurus [48]

Answer:

(a) Initial volume will be 7.62 L

(b) Final temperature will be 303.85 K

Explanation:

We have given one mole of ideal gas done 3000 J

So work done W = 3000 J

Let initial volume is $V_1$ and initial pressure $P_1=1atm$ ( As pressure is constant )

Final volume $V_2=25L$ = 0.025 $m^3$

Number of moles n = 1

(B) From ideal gas of equation we know that $PV=nRT$

So $1.01\times 10^5\times0.025=1\times 8.31\times T$

T = 303.85 Kelvin

(B) For isothermal process work done is equal to

$W=nRTln\frac{V_2}{V_1}$

$3000=1\times 8.314\times 303.85\times ln\frac{0.025}{V_1}$

$ln\frac{0.025}{V_1}=1.1881$

$\frac{0.025}{V_1}=3.2808$

$V_2=0.00846m^3=7.62L$

So initial volume will be 7.62 L

5 0

3 years ago

When applying a horizontal force of 30N, an object of mass 6 kg accelerates at 4m/s2. The force of friction on the surface must

Rus_ich [418]

Using Newton's Second Law, F = ma, where F is the net force

So the net force is:

F = (6kg)(4m/s^2) = 24N

Since you are applying a horizontal force of 30N, we can find the force of friction by the difference of the net force and the applied force.

30N-24N = 6N

$F_{f} = 6N$

4 0

3 years ago

1. A particular lever is 90.0% efficient. If 50.0 J of work are done on the lever, then how much work does the lever do on its l

laila [671]

Answer:

Explanation:

Using the efficiency formula;

Efficiency = Work done by the machine (output)/work done on the machine (input) ×100%

Efficiency =w/50 ×100

90 = 100w/50

Cross multiply

90×50 = 100W

4500 = 100W

W = 4500/100

W = 45Joules

Hence the lever does 45Joules of work on its load

2) Mechanical Advantage= Load/Effort

Given

MA = 4

Load = 500N

4 = 500/Effort

Effort = 500/4

Effort =125N

Hence the effort required to lift the load is 125N

8 0

3 years ago