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Verizon [17]
3 years ago
8

According to a certain estimate, the depth N(t), in centimeters, of the water in a certain tank at t hours past 2:00 in the morn

ing is given by N(t)= -20(t - 5)^2 + 500 for 0 ≤ t ≤ 10. According to this estimate, at what time in the morning does the depth of the water in the tank reach its maximum?a) 5:30 b) 7:00 c) 7:30 d) 8:00 e) 9:00
Physics
1 answer:
never [62]3 years ago
6 0

Answer:

b) 7.00

Explanation:

N( t ) = -20( t - 5 )²

dN/ dt = -20 x 2 ( t - 5 )

For maximum N ( depth )

dN/dt = 0

- 40 ( t - 5 ) = 0

t = 5

So at 2 + 5 = 7 .00 am depth of water reaches its maximum.

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Two for are at an angle at 120 ,the bigger forces is 40N and the resultant is perpendicular to the smaller one. find the smaller
Nadya [2.5K]

Answer:

smaller force is 20

Explanation:

Let, magnitude of the smaller force be F Newton.

Now, the resultant force makes an angle 90° with the smaller force. So, angle between resultant force and the larger force = (120° - 90°) = 30°.

So, tan 30° = (F * sin 120°) / (40 + F * cos 120°)

(1 / √3) = {F * (√3) / 2} / {40 + F * (- 1 / 2)}

80 - F = 3F

4F = 80

F = 20.

So, magnitude of smaller force is 20 Newtons.

3 0
2 years ago
A 10-kilogram bicycle is traveling at a speed of 2m/s. what is the bike's kinetice energy?
madam [21]
The kinetic energy of an object of mass m moving with speed v is given by:
K= \frac{1}{2}mv^2
For the bicycle in our problem, m=10 kg and v=2 m/s, so the kinetic energy is
K= \frac{1}{2}(10 kg)(2 m/s)^2=20 J
4 0
3 years ago
A bar on a hinge starts from rest and rotates with an angular acceleration α = 12 + 5t, where α is in rad/s2 and t is in seconds
Rama09 [41]

Answer:

Ф = 239.73 rad

Explanation:

α = 12 + 15×t

W = ∫α×dt

   = ∫(12 + 5×t)×dt

   = 12×t + 2.5×t^2

then:

Ф = ∫W×dt

   = ∫(12×t + 2.5×t^2)dt

   = 6×t^2 + 5/6×t^3

therefore the angle at t = 4.88s is:

Ф = 6×(4.88)^2 + 5/6×(4.88)^3

   = 239.73 rad    

5 0
3 years ago
15) What is the frequency of a pendulum that is moving at 30 m/s with a wavelength of .35 m?
____ [38]

A pendulum is not a wave.

-- A pendulum doesn't have a 'wavelength'.

-- There's no way to define how many of its "waves" pass a point
every second.

--  Whatever you say is the speed of the pendulum, that speed
can only be true at one or two points in the pendulum's swing,
and it's different everywhere else in the swing.

-- The frequency of a pendulum depends only on the length
of the string from which it hangs.


If you take the given information and try to apply wave motion to it:

             Wave speed = (wavelength) x (frequency)

             Frequency  =  (speed) / (wavelength) ,

you would end up with

             Frequency = (30 meter/sec) / (0.35 meter) = 85.7 Hz

Have you ever seen anything that could be described as
a pendulum, swinging or even wiggling back and forth
85 times every second ? ! ?     That's pretty absurd. 

This math is not applicable to the pendulum.

6 0
3 years ago
While traveling along a highway a driver slows from 31 m/s to 15 m/s in 8 seconds. What is the automobile’s acceleration? (Remem
MaRussiya [10]

Answer:

The automobile's acceleration in that time interval is -2 m/s^2

Explanation:

The acceleration is defined as the rate of change of the velocity.

The average acceleration in a given lapse of time is calculated as:

A = (final velocity - initial velocity)/time.

In this case, we have:

initial velocity = 31 m/s

final velocity = 15 m/s

time = 8 seconds.

Then the average acceleration is:

A = (15m/s - 31m/s)/8s = -2 m/s^2

8 0
2 years ago
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