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Arisa [49]
3 years ago
9

A coin is placed 32 cm from the center of a horizontal turntable, initially at rest. The turntable then begins to rotate. When t

he speed of the coin is 110 cm/s (rotating at a constant rate), the coin just begins to slip. The acceleration of gravity is 980 cm/s^2 . What is the coefficient of static friction between the coin and the turntable?
Physics
1 answer:
pashok25 [27]3 years ago
6 0

Answer:

0.39

Explanation:

distance from the center (r) = 32 cm = 0.32 m

speed of the coin (v) = 110 cm/s = 1.1 m/s

acceleration due to gravity (g) = 980 m/s^{2} = 9.8 m/s^{2}

find the coefficient of static friction (k) between the coin and the turn table

frictional force = kmg

before the table begins to move, the frictional force balances the centripetal force (\frac{mv^{2} }{r})

therefore

frictional force = centripetal force

kmg = \frac{mv^{2} }{r}

kg = \frac{v^{2} }{r}

k = \frac{v^{2} }{r} ÷ g

k = \frac{1.1^{2} }{0.32} ÷ 9.8 = 0.39

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A helicopter is traveling with a velocity of 12 m/s directly upward.
Irina-Kira [14]

Answer:

H = 27.35 m

Explanation:

From projectile motion, we know that;

h = (v_o)²/2g

Where;

v_o = 12 m/s

g = 9.8 m/s²

Thus;

h = 12²/(2 × 9.8)

h = 144/19.6

h = 7.35 m

Now, we are told that when the man is 20 m above the pillow, he lets go of

the rope.

Thus, greatest height reached by the man above the ground is;

H = 20 + h

H = = 20 + 7.35

H = 27.35 m

5 0
3 years ago
find the time taken, if the speed of a train increased from 72 km/hr to 90 km/hr for 234 km. leave your answer in seconds
Airida [17]

Answer:

Time taken = 10400 s

Explanation:

Given:

Initial speed of the train, u=72\textrm{ km/h}=72\times \frac{5}{18}=20\textrm{ m/s}

Final speed of the train, v=90\textrm{ km/h}=90\times \frac{5}{18}=25\textrm{ m/s}

Displacement of the train, S=234\textrm{ km}=234\times 1000=234000\textrm{ m}

Using Newton's equation of motion,

v - u = at\\a=\frac{v-u}{t}

Now, using Newton's equation of motion for displacement,

v^{2}-u^{2}=2aS

Now, plug in the value of a=\frac{v-u}{t} in the above equation. This gives,

v^{2}-u^{2}=2\times \frac{v-u}{t}\times S\\(v+u)(v-u)=\frac{2(v-u)S}{t}\\t=\frac{2(v-u)S}{(v+u)(v-u)}\\t=\frac{2S}{v+u}

Now, plug in 234000 m for S, 25 m/s for v and 20 m/s for u. Solve for t.

t=\frac{2S}{v+u}\\t=\frac{2\times 234000}{25+20}\\t=\frac{468000}{45}=10400\textrm{ s}

Therefore, the time taken by the train is 10400 s.

3 0
4 years ago
N a scientific investigation, what is the name for a prediction that can be tested?
ELEN [110]

A hypothesis is an educated prediction that can be tested.

8 0
4 years ago
The stone, which weighs 400 g, is thrown upwards at a speed of 20 m / s. Climbed to a height of 12 m. Determine: what is equal t
maxonik [38]

Given that,

Mass of the stone, m = 400 g = 0.4 kg

Initial speed, u = 20 m/s

It is climbed to a height of 12 m.

To find,

The work done by the resistance force.

Solution,

Let v is the final speed. It can be calculated by using the conservation of energy.

v=\sqrt{2gh} \\\\v=\sqrt{2\times 9.8\times 12} \\\\v=15.33\ m/s

Work done is equal to the change in kinetic energy. It can be given as follows :

W=\dfrac{1}{2}m(v^2-u^2)\\\\=\dfrac{1}{2}\times 0.4\times (15.33^2-20^2)\\\\=-32.99\ J

So, the required work done is 32.99 J.

3 0
3 years ago
1.
ale4655 [162]

Answer:

5.0 atm

Explanation:

P₁V₁=P₂V₂

P₁V₁/V₂=P₂

(1)(2.5)/(0•50)=P₂

P₂=5

Pressure is now 5.0 atm

8 0
3 years ago
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