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den301095 [7]
3 years ago
15

A 10-kg object is dropped from rest. after falling a distance of 50 m, it has a speed of 26 m/s. what is the change in mechanica

l energy caused by the dissipative (air) resistive force on the object during this descent?
Physics
1 answer:
likoan [24]3 years ago
4 0

The change in mechanical energy caused by the dissipative resistance force is equal to, difference between the potential energy and kinetic energy of the object.

Potential energy of the object, P.E = mgh

m is mass of the object = 10 kg

g is acceleration due to gravity = 9.8 m/s²

h= height from which it is dropped =50 m

Substituting the value we get,

P.E = 10×9.8×50 = 4900 J

Kinetic energy of the object, K.E = \frac{1}{2}mv^{2}

v is the velocity of the object = 26 m/s²

K.E = (1/2)×10×(26)²

= 3380 J

Change in mechanical energy caused by dissipative force = P.E ₋ K.E

= 4900 ₋ 3380 = 1520 J

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4. A massless spring hangs from the ceiling, and a mass is hung from the bottom of it. The mass is supported
MrRissso [65]

Answer:

The correct option is C: 0.31 s.

Explanation:

When the mass is then suddenly released we have:

F = k\Delta y

Where:

F is the force

k: is the spring constant

Δy: is the spring displacement

Since the tension in the spring is zero, the force is the weight:

F = mg

Where:

m is the mass of the object

g is the gravity

mg = k\Delta y    (1)

The oscillation period of the spring is given by:

T = 2\pi \sqrt{\frac{m}{k}}    (2)

By solving equation (1) for "k" and entering into equation (2) we have:

T = 2\pi \sqrt{\frac{m}{\frac{mg}{\Delta y}}}

T = 2\pi \sqrt{\frac{\Delta y}{g}}

Since the spring will osclliates in a position between the initial position (when it is at rest) and the final position (when the mass is released and reaches the bottom), we have Δy = 2.5 cm = 0.025 m:

T = 2\pi \sqrt{\frac{0.025 m}{10 m/s^{2}}} = 0.31 s                   

Hence, the oscillation period is 0.31 s.

The correct option is C: 0.31s.

I hope it helps you!                                                                                                      

7 0
4 years ago
If a bike rider travels 4 km in an hour,what is his speed measured in miles per hour?
tatyana61 [14]
<span>2.4854847</span> miles per hour
3 0
4 years ago
Read 2 more answers
A concert loudspeaker suspended high off the ground emits 33.0 W of sound power. A small microphone with a 0.600 cm2 area is 52.
Novay_Z [31]

Answer:

The sound intensity at the position of the microphone is 9.71\times10^{-4} W/m^{2}

Explanation

Sound intensity is given by the formula

I=\frac{P}{A}

Where I is the sound intensity, P is the power and A is the area.

Since the loudspeaker radiates sound in all directions, we have a spherical sound wave where the radius r is the distance of the microphone from the speaker.

∴ A is given by 4\pi r^{2} where r is the radius

From the question, P = 33.0W, r = 52.0m

I=\frac{P}{A} = \frac{P}{4\pi r^{2} }

I = \frac{33.0}{4\pi \times (52.0)^{2} }

∴ I = 9.71\times10^{-4} W/m^{2}

Hence, the sound intensity at the position of the microphone is 9.71 × 10⁻⁴ W/m²

7 0
3 years ago
What is the twisted ladder shape of the DNA called?
klio [65]

Answer:

Double helix

Explanation:

The Double helix is a DNA molecule. The two strands around the Double Helix is called the twisted ladder.

6 0
3 years ago
Read 2 more answers
A coin is placed on a vinyl stereo record that is making 33 1/3 revolutions per minute on a turntable. (a) In what direction is
mamaluj [8]

Answer: a) The acceletarion is directed to the center on the turntable. b) 5 cm; ac= 0.59 m/s^2; 10 cm, ac=1.20 m/s^2; 14 cm, ac=1.66 m/s^2

Explanation: In order to explain this problem we have to consider teh expression of the centripetal accelartion for a circular movement, which is given by:

ac=ω^2*r where ω and r are the angular speed and teh radios of the circular movement.

w=2*π*f

We know that the turntable is set to 33  1/3 rev/m so

the frequency 33.33/60=0.55 Hz

then w=2*π*0.55=3.45 rad/s

Finally the centripetal acceleration at differents radii results equal:

r= 0.05 m  ac=3.45^2*0.05=0.50 m/s^2

r=0.1  ac=3.45^2*0.1=1.20 m/s^2

r=0.14 ac=3.45^2*0.14=1.66 m/s^2

4 0
3 years ago
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