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Levart [38]
3 years ago
6

The height, h , in meters of a dropped object after t seconds can be represented by h ( t ) = − 4.9 t 2 + 136 . What is the inst

antaneous velocity of the object one second after it is dropped?
Physics
1 answer:
-BARSIC- [3]3 years ago
3 0

Answer:

The velocity of the object 1 s after it is dropped is -9.8 m/s.

Explanation:

Hi there!

The instantaneous velocity is defined by the change in height over a very small time. Mathematically, it is expressed as the derivative of the function h(t):

instantaneous velocity = dh/dt

dh/dt = h´(t) = -2 · 4.9 · t

h´(t) = -9.8 · t

Now we have to eveluate the function h´(t) at t = 1 s:

h´(1) = -9.8 · (1) = -9.8

The velocity of the object 1 s after it is dropped is -9.8 m/s.

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One end of a string is fixed. An object attached to the other end moves on a horizontal plane with uniform circular motion of ra
sveticcg [70]

Answer:

If both the radius and frequency are doubled, then the tension is increased 8 times.

Explanation:

The radial acceleration (a_{r}), measured in meters per square second, experimented by the moving end of the string is determined by the following kinematic formula:

a_{r} = 4\pi^{2}\cdot f^{2}\cdot R (1)

Where:

f - Frequency, measured in hertz.

R - Radius of rotation, measured in meters.

From Second Newton's Law, the centripetal acceleration is due to the existence of tension (T), measured in newtons, through the string, then we derive the following model:

\Sigma F = T = m\cdot a_{r} (2)

Where m is the mass of the object, measured in kilograms.

By applying (1) in (2), we have the following formula:

T = 4\pi^{2}\cdot m\cdot f^{2}\cdot R (3)

From where we conclude that tension is directly proportional to the radius and the square of frequency. Then, if radius and frequency are doubled, then the ratio between tensions is:

\frac{T_{2}}{T_{1}} = \left(\frac{f_{2}}{f_{1}} \right)^{2}\cdot \left(\frac{R_{2}}{R_{1}} \right) (4)

\frac{T_{2}}{T_{1}} = 4\cdot 2

\frac{T_{2}}{T_{1}} = 8

If both the radius and frequency are doubled, then the tension is increased 8 times.

5 0
3 years ago
a hot piece of copper is placed in an insulated cup. what is the final temperature of the water and copper?
slavikrds [6]

Answer:

Option C. 30°C.

Explanation:

The following data were obtained from the question:

Mass of water (Mw) = 0.5 Kg

Specific heat capacity of water (Cw) = 4.18 KJ/Kg°C

Initial temperature of water (Tw1) =

22°C

Change in temperature (ΔT) = T2 – Tw1 = T2 – 22°C

Mass of copper (Mc) = 0.5 Kg

Specific heat capacity of copper (Cc) = 0.386 KJ/kg°C

Initial temperature of copper (Tc1) = 115°C

Change in temperature (ΔT) = T2 – Tc1 = T2 – 115°C

Final temperature (T2) =..?

Note: Both the water and the piece copper will have the same final temperature and the heat will be zero since the water will cool the piece of copper.

Thus, we can determine the final temperature of the water and copper as follow:

Q = MwCwΔT + McCcΔT

0 = 0.5 x 4.18 x (T2 – 22) + 0.5 x 0.386 x (T2 – 115)

0 = 2.09 (T2 – 22) + 0.193 (T2 – 115)

0 = 2.09T2 – 45.98 + 0.193T2 – 22.195

Collect like terms

2.09T2 + 0.193T2 = 45.98 + 22.195

2.283T2 = 68.175

Divide both side by the coefficient of T2 i.e 2.283

T2 = 68.175/2.283

T2 = 29.8 ≈ 30°C

Therefore, the final temperature of water and copper is 30°C.

8 0
3 years ago
How is the ideal mechanical advantage of a wheel and axel calculated
kenny6666 [7]

Answer:

by being calculated <em>like duh</em>

Explanation:

5 0
4 years ago
Read 2 more answers
What is the λ (in m) of an electromagnetic wave that has a frequency of 5.68 x 107 Hz? Enter a numerical response in 3 significa
denpristay [2]

Answer:

Wavelength of electromagnetic wave will be 5.281 m

Explanation:

We have given frequency of electromagnetic wave is f=5.68\times 10^7Hz

Velocity of electromagnetic wave is c=3\times 10^8m/sec

We have to fond the wavelength of the electromagnetic wave

We know that velocity of electromagnetic eave is given by v=\lambda f, here \lambda is wavelength and f is frequency

So \lambda =\frac{v}{f}=\frac{3\times 10^8}{5.68\times 10^7}=5.281m

Wavelength of electromagnetic wave will be 5.281 m

6 0
3 years ago
Value of mass of a body is fixed everywhere. true or false<br>​
PSYCHO15rus [73]
Mass is the amount of particles present and weight is the amount of gravitational force experienced by a body. Since gravity changes from one celestial object to another, weight of a body changes accordingly. But it's mass remains constant since the amount of particles present in that object doesn't change anywhere
6 0
3 years ago
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