Ask question

Ask question

All categories

2 years ago

8

Briana swings a ball on the end of a rope in a circle. The rope is 1.5 m long. The ball completes a full circle every 2.2 s. Wha

t is the tangential speed of the ball? 0.68 m/s 2.1 m/s 4.3 m/s 9.2 m/s

2 answers:

schepotkina [342]2 years ago

9 0

The radius of the circular path is 1.5 m.

The circumference is then
$1.5\ m*2\pi=3\pi\ m$

The ball moves 3π m every 2.2 s, so the speed is
$\frac{3\pi\ m}{2.2\ s}\approx 4.3\ m/s$

expeople1 [14]2 years ago

6 0

Answer:

<em>C</em> - 4.3 m/s

♥

You might be interested in

A crane uses a block and tackle to lift a 2200N flagstone to a height of 25m

Cloud [144]

Remember the headline: ENERGY IS NEVER CREATED OR DESTROYED

The amount of energy before and after are always equal. All we ever do with energy is move it around from one place to another.

a). A crane can't create energy. Lifting the same rock in 20 different ways always takes the <u><em>same amount of work</em></u>. It doesn't matter whether one person picks the rock straight up, or 50 people get around it and lift it, or roll it up a ramp, or lift it with 16 pulleys and a mile of rope, or use a giant steam crane.

You want to lift a 2200N weight up 25m, you're going to have to supply

(2200N) x (25m) = <em>55,000 Joules</em> of work.

c). YOU put out 55,000 Joules of energy. It had to GO someplace. Where is it now ? ===> It's the potential energy the rock has now, from being 25m higher than it was before. That <em>55,000 Joules</em> is NOW the potential energy of the rock.

No energy was created or destroyed. It just got moved around.

55,000 Joules of energy began as nuclear energy in the core of the sun. Solar radiation carried it to the Earth. Plants absorbed it, and stored it as chemical energy. You ... or a cow that you ate later ... ate the plants and took the chemical energy. One way or the other, the chemical energy got stored in your blood and fat. When you needed to put it out somewhere, you moved it into your muscles, and they converted it into mechanical energy. Then you used the mechanical energy to exert forces. Today, you used the original 55,000 joules to lift the flagstone, and NOW that energy is in the flagstone, 25 meters up off the ground !

6 0

2 years ago

A rigid vessel of 0.06 m3 volume contains an ideal gas , CV =2.5R, at 500K and 1 bar.a). if 15000J heat is transferred to the ga

andreev551 [17]

Answer:

Given that

V= 0.06 m³

Cv= 2.5 R= 5/2 R

T₁=500 K

P₁=1 bar

Heat addition = 15000 J

We know that heat addition at constant volume process ( rigid vessel ) given as

Q = n Cv ΔT

We know that

P V = n R T

n=PV/RT

n= (100 x 0.06)(500 x 8.314)

n=1.443 mol

So

Q = n Cv ΔT

15000 = 1.433 x 2.5 x 8.314 ( T₂-500)

T₂=1000.12 K

We know that at constant volume process

P₂/P₁=T₂/T₁

P₂/1 = 1000.21/500

P₂= 2 bar

Entropy change given as

$\Delta S=nC_P\ln \dfrac{T_2}{T_1}-nR\ln \dfrac{P_2}{P_1}$

Cp-Cv= R

Cp=7/2 R

Now by putting the values

$\Delta S=nC_P\ln \dfrac{T_2}{T_1}-nR\ln \dfrac{P_2}{P_1}$

$\Delta S=1.443\times 3.5\times 8.314\ln \dfrac{1000.21}{500}-1.443\times 8.314\ln \dfrac{2}{1}$

a)ΔS= 20.79 J/K

b)

If the process is adiabatic it means that heat transfer is zero.

So

ΔS= 20.79 J/K

We know that

$\Delta S_{univ}=\Delta S_{syatem}+\Delta S_{surr}$

Process is adiabatic

$\Delta S_{surr}=0$

$\Delta S_{univ}=\Delta S_{syatem}+\Delta S_{surr}$

$\Delta S_{univ}= 20.79 +0$

$\Delta S_{univ}= 20.79$

3 0

2 years ago

Which of the following selections completes the following nuclear reaction?

Monica [59]

Answer:

n (a neutron)

Explanation:

For a chemical element:

- The lower subscript indicates the atomic number (the number of protons)

- The upper subscript indicates the mass number (the sum of protons and neutrons in the nucleus)

In the reaction described in the problem, we see that a gamma photon hits a nucleus of Calcium-40, which has

Z = 20 (20 protons)

A = 40 (40 protons+neutrons)

Which means that the number of neutrons is n = A - Z = 40 - 20 = 20

After the reaction, we have a nucleus of Calcium-39, which has

Z = 20 (20 protons)

A = 39 (39 protons+neutrons)

Which means that the number of neutrons is n = A - Z = 40 - 39 = 19

So, the nucleus has lost 1 neutron, which is the particle missing in the reaction.

3 0

2 years ago

Suppose you are measuring the height of a small child. What will determine the number if significant digits you record?

slega [8]

The number of significant digits of any measurement is determined by the instrument used for such measurement. For example, in this case, we have the height of a small child being measured. We can use a simple ruler for this, and we see that a ruler has ten divisions for 1 cm. This means that the ruler cannot measure beyond the size of 0.1 cm or 1 mm. Hence, when we report the height of the small child, we report it to one significant digit after the decimal place. As an example, if we measure a child's height to be 90 full cm divisions and 8 smaller divisions, we report it as 90.8 cm but not 90.83 or 90.86 cm.

8 0

2 years ago

: Two containers have a substantial amount of the air evacuated out of them so that the pressure inside is half the pressure at

ser-zykov [4K]

Complete Question

Two containers have a substantial amount of the air evacuated out of them so that the pressure inside is half the pressure at sea level. One container is in Denver at an altitude of about 6,000 ft and the other is in New Orleans (at sea level). The surface area of the container lid is A=0.0155 m. The air pressure in Denver is PD = 79000 Pa. and in New Orleans is PNo = 100250 Pa. Assume the lid is weightless.

Part (a) Write an expression for the force FNo required to remove the container lid in New Orleans.

Part (b) Calculate the force FNo required to lift off the container lid in New Orleans, in newtons.

Part (c) Calculate the force Fp required to lift off the container lid in Denver, in newtons.

Part (d) is more force required to lift the lid in Denver (higher altitude, lower pressure) or New Orleans (lower altitude, higher pressure)?

Answer:

a

The expression is $F_{No} = A [P_{No} - \frac{P_{sea}}{2}]$

b

$F_{No}= 7771.125 \ N$

c

$F_p = 2.2*10^{6} N$

d

From the value obtained we can say the that the force required to open the lid is higher at Denver

Explanation:

The altitude of container in Denver is $d_D = 6000 \ ft = 6000 * 0.3048 = 1828.8m$

The surface area of the container lid is $A = 0.0155m^2$

The altitude of container in New Orleans is sea-level

The air pressure in Denver is $P_D = 79000 \ Pa$

The air pressure in new Orleans is $P_{ro} = 100250 \ Pa$

Generally force is mathematically represented as

$F_{No} = \Delta P A$

So we are told the pressure inside is is half the pressure the at sea level so the the pressure acting on the container would

The pressure at sea level is a constant with a value of

$P_{sea} = 101000 Pa$

So the $\Delta P$ which is the difference in pressure within and outside the container is

$\Delta P = P_{No} - \frac{P_{sea}}{2}$

Therefore

$F_{No} = A [P_{No} - \frac{P_{sea}}{2}]$

Now substituting values

$F_{No} = 0.0155 [100250 - \frac{101000}{2}]$

$F_{No}= 7771.125 \ N$

The force to remove the lid in Denver is

$F_p = \Delta P_d A$

So we are told the pressure inside is is half the pressure the at sea level so the the pressure acting on the container would

The pressure at sea level is a constant with a value of

$P_{sea} = 101000 Pa$

At sea level the air pressure in Denver is mathematically represented as

$P_D = \rho g h$

=> $g = \frac{P_D}{\rho h}$

Let height at sea level is h = 1

The air pressure at height $d_D$

$P_d__{D}} = \rho gd_D$

=> $g = \frac{P_d_D}{\rho d_D}$

Equating the both

$\frac{P_D}{\rho h} = \frac{P_d_D}{\rho d_D}$

$P_d_D = P_D * d_D$

Substituting value

$P_d__{D}} = 1828.2 * 79000$

$P_d__{D}} = 1.445*10^{8} Pa$

So

$\Delta P_d = P_{d} _D - \frac{P_{sea}}{2}$

=> $\Delta P_d = 1.445 *10^{8} - \frac{101000}{2}$

$\Delta P_d = 1.44*10^{8}Pa$

So

$F_p = \Delta P_d A$

$= 1.44*10^8 * 0.0155$

$F_p = 2.2*10^{6} N$

6 0

2 years ago