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maksim [4K]
3 years ago
13

A student holds a bike wheel and starts it spinning with an initial angular speed of 9.0 rotations per second. The wheel is subj

ect to some friction, so it gradually slows down. In the 10.0 s period following the inital spin, the bike wheel undergoes 65.0 complete rotations. Assuming the frictional torque remains constant, how much more time Δ t s will it take the bike wheel to come to a complete stop?
Physics
1 answer:
KATRIN_1 [288]3 years ago
6 0

Answer:

\Delta t = 8 s

Explanation:

As we know that the angular acceleration of the wheel due to friction is constant

so we can use kinematics

\theta = \omega_i t + \frac{1}{2}\alpha t^2

so we have

(65 \times 2\pi) = (2\pi \times 9)(10) + \frac{1}{2}(\alpha)(10^2)

130\pi = 180\pi + 50 \alpha

\alpha = -\pi rad/s^2

now time required to completely stop the wheel is given as

\omega_f = \omega_i + \alpha t

0 = (2\pi \times 9) + (-\pi) t

t = 18 s

now time required to stop the wheel is given as

\Delta t = 18 - 10

\Delta t = 8 s

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Solve for A if F=MA and F=100 and M=25?
inn [45]

Answer:

<h3>\boxed{ \boxed{ \bold{A = 4}}}</h3>

Explanation:

Given,

F = 100 , M = 25

Now, let's find the value of A

\sf{F = MA}

plug the values

⇒\sf{100 = 25 A}

Swap the sides of the equation

⇒\sf{25A = 100}

Divide both sides of the equation by 25

⇒\sf{ \frac{25A}{25}  =  \frac{100}{25} }

Calculate

⇒\sf{A = 4}

Hope I helped!

Best regards!!

5 0
3 years ago
Read 2 more answers
A constant tone is being applied to a speaker. The voltage across the speaker is 5 volts. The voltage across the speaker is incr
lubasha [3.4K]

Answer:

decibel gain is 10 db

Explanation:

given data

voltage v1 =  5 volts

voltage v2 = 15 volts

to find out

decibel gain

solution

we have given that 5 volt voltage that is increase to 15 volts

so

we know here decibel gain formula that is

decibel gain = 20 log(v2/v1)   ....................1

put here value of v1 and v2  in equation 1

decibel gain = 20 log(15/5)

decibel gain = 20 log3

decibel gain = 20 × 0.4771

decibel gain = 9.54 db = approx 10 db

so decibel gain is 10 db

5 0
3 years ago
Read 2 more answers
A car of mass 2200 kg collides with a truck of mass 4500 kg, and just after the collision the car and truck slide along, stuck t
katovenus [111]

Answer:

37.7m/s: principle of conservation of momentum

Explanation:

The principle to make use of is the principle of conservation of momentum which States that the sum of momentum of bodies before collision is equal to the sum of momentum of bodies after collision. This bodies will move with the same velocity after collision.

Momentum = Mass × velocity

For car of mass 2200kg moving with velocity 33m/s:

Momentum of car before collision = 2200×33

= 72,600kgm/s

For the truck of mass 4500kg;

Momentum = 4500 ×(22-(-18)

= 4500×40

= 180000kgm/s

After collision, their momentum is:

Momentum after collision = (2200+4500)v

= 6700v

Using the principle above to get the common velocity v we have

72600+180000 = 6700v

252600 = 6700v

v = 252600/6700

v = 37.7m/s

7 0
3 years ago
Will give brainlist
Aleks [24]

Answer:

Yes

Explanation:

There was a force, 500 lb.

and a motion in the direction of the force, in this case a negative direction.

Therefore the lifter did negative work on the mass of the  barbell against gravity.

Gravity would do positive work against the mass of weight when the lifter lowers the barbell as the force vector and the motion vector are in the same direction.

5 0
3 years ago
Why do some devices use batteries and other devices use a wall outlet for power?
Alina [70]

Some devices are used while moving around from place to place ... like in the car, on a bicycle, running, or walking the dog. If not for batteries, those devices would need very long extension cords.

3 0
3 years ago
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