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Sergeeva-Olga [200]
2 years ago
13

Pls help asap

Physics
2 answers:
RoseWind [281]2 years ago
8 0
I’m pretty sure the answer is a
Ira Lisetskai [31]2 years ago
3 0

Answer:

D

Explanation:

i took lots of time on the lesson

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You have a horizontal grindstone (a disk) that is 86 kg, has a 0.33 m radius, is turning at 92 rpm (in the positive direction),
Rudiy27

Answer:

a) α = 0.338 rad / s²  b)   θ = 21.9 rev

Explanation:

a) To solve this exercise we will use Newton's second law for rotational movement, that is, torque

    τ = I α

    fr r = I α

Now we write the translational Newton equation in the radial direction

    N- F = 0

    N = F

The friction force equation is

    fr = μ N

    fr = μ F

The moment of inertia of a saying is

    I = ½ m r²

Let's replace in the torque equation

    (μ F) r = (½ m r²) α

    α = 2 μ F / (m r)

    α = 2 0.2 24 / (86 0.33)

    α = 0.338 rad / s²

b) let's use the relationship of rotational kinematics

    w² = w₀² - 2 α θ

    0 = w₀² - 2 α θ

    θ = w₀² / 2 α

Let's reduce the angular velocity

     w₀ = 92 rpm (2π rad / 1 rev) (1 min / 60s) = 9.634 rad / s

    θ = 9.634 2 / (2 0.338)

     θ = 137.3 rad

Let's reduce radians to revolutions

    θ = 137.3 rad (1 rev / 2π rad)

    θ = 21.9 rev

7 0
3 years ago
Newton has Three Laws of Motion. Seat belts are used to help keep the passengers remaining in their seats during an accident. If
Jobisdone [24]
That is the 1st Law
Your welcome and PLEASE RATE TO KEEP HELPING YOU
5 0
3 years ago
Show that (a)KE=1/2mv2
evablogger [386]

Answer:

\boxed{ \bold{ \huge{ \boxed{ \sf{see \: below}}}}}

Explanation:

\underline{ \bold{ \sf{To \: prove \: that \: kinetic \: energy =  \frac{1}{2} m {v}^{2} }}}

Let us consider, a body of mass ' m ' is lying at rest ( initial velocity = 0 ) on a smooth surface. Let a constant force F displaces this body in its own direction by a displacement ' d '. Let 'v' be it's final velocity. The work done ' W ' by the force is given by :

\sf{W = FD}

⇒\sf{W = m \:  \times a \:  \times s} \:  \:  \:  \:  \:  \:  \:  \:  \: ( \: ∴ \: f \:  =  \: ma \: ; \: s \:  = d)

⇒\sf{W = m \:  \times  \frac{v - u}{t}  \times  \frac{u + v}{2}  \times t \:  \:  \:  \:  \:  \:  \:  \:  \: (∴ \: a =   \frac{v - u}{t} and \: s =  \frac{u + v}{2}  \times t}

⇒\sf{W = m \times  \frac{ {v}^{2}  -  {u}^{2} }{2} }

⇒\sf{W =  \frac{1}{2} m {v}^{2}  \:  \:  \:  \:  \:  \:  \:  \:  \:  \:  \:  \: (since, \: initial \: velocity(u) = 0)}

The work done becomes the kinetic energy of the body. Thus, the kinetic energy of a body of mass ' m : moving with the velocity equal to 'v ' is 1 / 2 mv²

∴ \sf{KE=  \frac{1}{2} m {v}^{2} }

\sf{ \underline{ \bold{  {proved}}}}

Hope I helped!

Best regards!!

5 0
3 years ago
You machine that tells you exactly how much work in joules is put into a machine and how much work produced. The reading that yo
marysya [2.9K]
Friction in the machine turned 15 joules of the energy input into heat. If you were monitoring the parts of the machine closely, you would notice that some of them warmed up.
7 0
3 years ago
A water skier notices that the distance between successive wave crest is 12 meters. The wave crests pass his boat every 4.8 seco
Alenkinab [10]

Answer:

The velocity of wave=2.5 m/s

Explanation:

We are given that

The distance between successive wave crest=\lambda=12m

Time =2.8 s

We have to find the the velocity of wave.

Frequency of wave=\nu=\frac{1}{T}=\frac{1}{4.8} s=0.2083 Hz

The relation between frequency, wavelength and velocity is given by

\lambda=\frac{v}{\nu}

12=\frac{v}{\frac{1}{4.8}}

v=12\times \frac{1}{4.8}=2.5 m/s

Hence, the velocity of wave= 2.5 m/s

6 0
3 years ago
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