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Andrei [34K]
2 years ago
7

postal worker on a bicycle travels at an average speed of 4m/s for 3 minutes. Work out how far she travelled.

Physics
2 answers:
WARRIOR [948]2 years ago
8 0
The postal worker traveled 720 meters. <span />
JulsSmile [24]2 years ago
6 0

Answer:

Distance, d = 720 m

Explanation:

It is given that,

Average speed of the bicycle, s = 4 m/s

Time taken, t = 3 minutes = 180 seconds

We have to find the distance travelled by the postal worker. Distance travelled is equal to the product of velocity and time. Mathematically, it can be written as :

d = s × t

d = 4 m/s × 180 s

d = 720 m

Hence, the distance travelled by the postal worker is 720 m.

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How many calories are equal to one BTU? (One calorie = 4.186 J, one BTU = 1 054 J.)
I am Lyosha [343]
<h2>Option C is the correct answer.</h2>

Explanation:

We need to find how many calories is 1 BTU.

Given

          1 BTU = 1054 J

          1 calorie = 4.186 J

So we have

          1 BTU = 4.186 x 251.79 J

          1 BTU =251.79 calorie

          1 BTU = 252 calorie.

Option C is the correct answer.

3 0
2 years ago
A single crystal of aluminum is oriented for a tensile test such that its slip plane normal makes angle of 28.1 with the tensil
NISA [10]

Answer:

we have to find out the critical resolved shear stress. As it it given in the question

Ф = 28.1°and the possible values for λ are 62.4°, 72.0° and 81.1°.

a) Slip will occur in the direction where cosФ cosλ are maximum. Cosine for all possible λ values are given as follows.

cos(62.4°) = 0.46

cos(72.0°) = 0.31

cos(81.1°) = 0.15

Thus, the slip direction is at the angle of 62.4° along the tensile axis.

b) now the critical resolved shear stress can be find out by the following equation.

τ_{crss} = σ_{Y} ( cosФ cosλ)_{max}

now by putting values,

     = (1.95MPa)[ cos(28.1) cos(62.4)] = 0.80 MPa (114 Psi) 7.23

3 0
2 years ago
Calculate the binding energy e of the boron nucleus 11 5b (1ev=1.602×10−19j). express your answer in millions of electron volts
nignag [31]
<span>Depends on the precision you're working to. proton mass ~ 1.00728 amu neutron mass ~ 1.00866 amu electron mass ~ electron mass = 0.000549 amu Binding mass is: mass of constituents - mass of atom Eg for nitrogen: (7*1.00728)-(7*1.00866)-(7*0.000549) -14.003074 = 0.11235amu Binding energy is: E=mc^2 where c is the speed of light. Nuclear physics is usually done in MeV[1] where 1 amu is about 931.5MeV/c^2. So: 0.11235 * 931.5 = 104.6MeV Binding energy per nucleon is total energy divided by number of nucleons. 104.6/14 = 7.47MeV This is probably about right; it sounds like the right size! Do the same thing for D/E/F and recheck using your numbers & you shouldn't go far wrong :) 1 - have you done this? MeV is Mega electron Volts, where one electronVolt (or eV) is the change in potential energy by moving one electron up a 1 volt potential. ie energy = charge * potential, so 1eV is about 1.6x10^-19J (the same number as the charge of an electron but in Joules). It's a measure of energy, but by E=mc^2 you can swap between energy and mass using the c^2 factor. Most nuclear physicists report mass in units of MeV/c^2 - so you know that its rest mass energy is that number in MeV.</span>
7 0
2 years ago
(8%) Problem 9: Helium is a very important element for both industrial and research applications. In its gas form it can be used
exis [7]

Answer:

2046.37 kPa

Explanation:

Given:

Number of moles, n = 125

Temperature, T = 20° C = 20 + 273 = 293 K

Radius of the cylinder, r = 17 cm = 0.17 m

Height of the cylinder, h = 1.64 m

thus,

volume of the cylinder, V = πr²h

= π × 0.17² × 1.64

= 0.148 m³

Now,

From the ideal gas law

we have

PV = nRT

here,

P is the pressure

R is the ideal gas constant = 8.314  J / mol. K

thus,

P × 0.148 = 125 × 8.314 × 293

or

P × 0.148 = 304500.25

or

P = 2046372.64 Pa = 2046.37 kPa

6 0
2 years ago
Liam throws a water balloon horizontally at 8.2 m/s out of a window 18 m from the ground.
Alecsey [184]

Time taken by the water balloon to reach the bottom will be given as

h = \frac{1}{2} gt^2

here we know that

h = 18 m

g = 9.8 m/s^2

now by the above formula

18 = \frac{1}{2}*9.8* t^2

18 = 4.9 t^2

t = 1.92 s

now in the same time interval we can say the distance moved by it will be

d = v_x * t

d = 8.2 * 1.92 = 15.7 m

so it will fall at a distance 15.7 m from its initial position

5 0
2 years ago
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