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4 years ago

15

When is acceleration positive, negative, and zero? Calculate the average speed if I walk to class at a speed of 20 meters/minute

for the first 2 minutes and run when they start to play 21 savage at a rate of 50 meters/minute for the last 3 minutes.

1 answer:

Marrrta [24]4 years ago

6 0

Part A: a->positive when velocity is increasing a->negative when velocity is decreasing a->zero when velocity is constant

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If a sound wave is produced with a wavelength of 1.04m what is the waves frequency

dmitriy555 [2]

You should just ask the wave

5 0

3 years ago

An airplane propeller is 2.68 m in length (from tip to tip) and has a mass of 107 kg. When the airplane's engine is first starte

telo118 [61]

Answer:

a)30.14 rad/s2

b)43.5 rad/s

c)60633 J

d)42 kW

e)84 kW

Explanation:

If we treat the propeller is a slender rod, then its moments of inertia is

$I =\frac{mL^2}{12} = \frac{107*2.68^2}{12} = 64.04 kgm^2$

a. The angular acceleration is Torque divided by moments of inertia:

$\alpha = \frac{T}{I} = \frac{1930}{64.04} = 30.14 rad/s^2$

b. 5 revolution would be equals to $10\pi$ rad, or 31.4 rad. Since the engine just got started

$\omega^2 = 2\alpha\theta = 2*30.14*31.4 = 1893.5$

$\omega = \sqrt{1893.5} = 43.5 rad/s$

c. Work done during the first 5 revolution would be torque times angular displacement:

$W = T*\theta = 1930 * 31.4 = 60633 J$

d. The time it takes to spin the first 5 revolutions is

$t = \frac{\omega}{\alpha} = \frac{43.5}{30.14} = 1.44 s$

The average power output is work per unit time

$P = \frac{W}{t} = \frac{60633}{1.44} = 41991 W$ or 42 kW

e.The instantaneous power at the instant of 5 rev would be Torque times angular speed at that time:

$P_i = T*\omega = 1930*43.5=83983 W$ or 84 kW

7 0

3 years ago

Charge A and charge B are 3.00 m apart, and charge A is +1.44 C and charge B is +3.10 C. Charge C is located between them at a c

Sidana [21]

Answer:

the distance from charge A to C is r₁₃= 1.216 m

Explanation:

following Coulomb's law , the force exerted by 2 point charges between themselves is:

F= k*q₁*q₂/r₁₂² , where q is charge , r is distance and 1 and 2 represents the charge A and charge B respectively , k=constant

since C ( denoted as 3) is at equilibrium

F₁₃=F₂₃

k*q₁*q₃/r₁₃²=k*q₂*q₃/r₂₃²

q₁/r₁₃²=q₂/r₂₃²

r₁₃²/q₁=r₂₃²/q₂

r₂₃=r₁₃*√(q₂/q₁)

since C is at rest and is co linear with A and B ( otherwise it would receive a net force in either vertical or horizontal direction) , we have

r₁₃+r₂₃=d=r₁₂

r₁₃+r₁₃*√(q₂/q₁)=d

r₁₃*(1+√(q₂/q₁))=d

r₁₃=d/(1+√(q₂/q₁))

replacing values

r₁₃=d/(1+√(q₂/q₁)) = 3.00 m/(1+√(3.10 C/1.44 C)) = 1.216 m

thus the distance from charge A to C is r₁₃= 1.216 m

7 0

3 years ago

A car accelerates from rest to 90m/s in 3 seconds. What is the acceleration and how far did it travel?

Inessa [10]

Answer:

Explanation:

1.)acceleration= final velocity-initial velocity/time

90m/s-0m/s /3seconds

=30m/s^2

2.) distance= speed*time

90m/s*3seconds

=270m

4 0

3 years ago

A bird carries a 25 g oyster to a height of 11m what is the gravitational potential energy of the oyster

garik1379 [7]

Given data:

Mass of oyster (m) = 25 g,

= 0.025 kg (<em> since 1 Kg = 1000 g)</em>

Height of oyster (h) = 11 m,

determine gravitational potential energy (GPE) = ?

Gravitational potential energy is energy of an object possesses because of its position on the earth. The amount of gravitational potential energy of an object on earth depends on its<em> mass</em> and<em> height </em>from the earth.

Mathematically,

GPE = m. g. h <em>Joules</em>

<em> Where, </em>

<em> </em>GPE =<em> </em>gravitational potential energy,

<em> </em> m = mass of object in Kg,

g = gravitational force in m/s², g = 9.8 m/s²

h = height of the object in meters,

Now substituting all the values in the equation GPE

GPE = 0.025 Kg × 9.8 m/s² × 11 m

= 2.695 J

Gravitational potential energy of the oyster is 2.695 J

7 0

3 years ago