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3 years ago

A football is thrown due north across a 40 meter river and it takes 2 seconds to cover that distance.

Physics

1 answer:

Alexxx [7]3 years ago

6 0

Answer:

I. Speed = 20m/s

II. Velocity = 20m/s due North.

Explanation:

Given the following data;

Distance = 40m

Time = 2secs

To find the speed;

Mathematically, speed is given by the formula;

$Speed = \frac{distance}{time}$

Substituting into the equation, we have;

$Speed = \frac{40}{2}$

Speed = 20m/s.

In physics, we use the same formula for calculating speed and velocity. The only difference is that speed is a scalar quantity and as such has magnitude but no direction while velocity is a vector quantity and as such it has both magnitude and direction.

$Velocity = \frac{distance}{time}$

Therefore, the velocity is 20m/s due North.

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Longitudinal sound waves cannot propagate through

strojnjashka [21]

Answer:

A vacuum

Explanation:

Sound waves are examples of mechanical waves. Mechanical waves are waves which are transmitted through the vibrations of the particles in a medium.

For example, sound waves in air consist of oscillations of the air particles, which vibrate back and forth (longitudinal wave) along the direction of propagation of the wave itself.

Given this definition of mechanical wave, we see that such a wave cannot propagate if there is no medium, because there are no particles that would oscillate. Therefore, among the choices given, the following one:

a vacuum

represent the only situation in which a sound wave cannot propagate through: in fact, there are no particles in a vacuum, so the oscillations cannot occur. In all other cases, instead, sound waves can propagate.

3 0

3 years ago

Please help me out someone nothing helping me out please someone

Zolol [24]

Well i think the best answer would be A

8 0

3 years ago

Consider an oblique shock wave with a wave angle of 35 o . Upstream of the wave, the static pressure and temperature are 2,000 l

ziro4ka [17]

Answer:

The pressure is 6570 lbf/ft²

The temperature is 766 ⁰R

The velocity is 2746.7 ft/s

deflection angle behind the wave is 17.56⁰

Explanation:

Speed of air at initial condition:

$a_1 = \sqrt{\gamma RT } = \sqrt{1.4* 1716*520 } = 1117.70 \ ft/s$

γ is the ratio of specific heat, R is the universal gas constant, and T is the initial temperature.

initial mach number

$M_1 = \frac{v_1}{a_1} = \frac{3355}{1117.7} = 3$

then, $M_n = M_1sin \beta = 3sin(35) = 1.721$

based on the values obtained, read off the following from table;

P₂/P₁ = 3.285

T₂/T₁ = 1.473

Mₙ₂ = 0.6355

Thus;

P₂ = 3.285P₁ = 3.285(2000) = 6570 lbf/ft²

T₂ = 1.473T₁ = 1.473(520⁰R) = 766 ⁰R

Again; to determine the velocity and deflection angle, first we calculate the mach number.

$M_t_1 = M_1cos \beta = 3 cos(35) = 2.458$

$w_2 = a_1M_t_1 = 2.458(1117.70) = 2746.7 \ ft/s$

$a_2 = \sqrt{\gamma RT_2} = \sqrt{1.4*1718*766} = 1357.34 \ ft/s$

$v_2 = a_2M_n_2 = 1357.34(0.6355) = 862.59 \ ft/s$

$Tan(\beta -\theta) = \frac{v_2}{w_2} = \frac{862.59}{2746.7} \\\\Tan(\beta -\theta) = 0.314\\\\\beta -\theta= 17.44\\\\\theta = \beta - 17.44 = 17.56^o$

6 0

3 years ago

Section 1 - Question 30

stira [4]

Answer : A
Explanation: he is motivated to make the football team

3 0

3 years ago

a large bottle contains a number of medicinal tablets each having a mass of 250mg the mass of all the tablets is 0.5kg calculate

lys-0071 [83]

Considering the change of units and rule of three, the number of tablets in the bottle is 2,000.

First of all, you know that each medicinal tablet has a mass of 250 mg, while the mass of all tablets is 0.5 kg. You can see that the measurements are in different units of measurement, so you must make a change of units so that they are in the same units.

So, knowing that 1 kg is equal to 1,000,000 mg, you can apply the following rule of three: if 1 kg is equal to 1,000,000 mg, 0.5 kg is equal to how many mg?

1 kg ⇒ 1,000,000 mg

0.5 kg ⇒ x mg

So: $x=\frac{0.5 kgx1,000,000 mg}{1 kg}$

x= 500,000 mg

Then, you know that each medicinal tablet has a mass of 250 mg, while the mass of all tablets is 500,000 mg. Now that the values are in the same units, to calculate the number of medicinal tablets you must apply the following rule of three: if 1 tablet has a mass of 250 mg, how many tablets have a mass of 500,000 mg?

$number of medicinal tablets=\frac{500,000 mgx1 tablet}{250 mg}$

number of medicinal tablets= 2,000

Finally, the number of tablets in the bottle is 2,000.

Learn more:

3 0

3 years ago