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Yuri [45]
3 years ago
7

A boy is swinging a yo-yo with mass 0.25 kg in a circle with radius 1 m at a speed of 6 m/s. What is the tension in the string c

onnecting the yo-yo to the boy's finger, disregarding the effect of gravity?
A. 20N
B. 12N
C. 35N
D. 9N
Physics
1 answer:
Paladinen [302]3 years ago
5 0

Answer:

D. 9 N

Explanation:

The tension on the string is equivalent to the centripetal force.

Centripetal force is the force exerted by an object in circular motion or path towards the center of the circular path.

Centripetal force = mv²/r

where m is the mass of the object, v is the velocity and r is the radius of the circular path.

Centripetal force = (0.25 kg × 6²)/ 1

                            = 9 N

Thus, the tension on the string is 9 N

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A certain nuclear power plant is capable of producing 1.2×10^9 W of electric power. During operation of the reactor, mass is con
alukav5142 [94]

Answer:

0.00016 kg

Explanation:  

Given:

Power = P = 1.2 × 10⁹ Watts

Power =  work done / Time

efficiency = 0.30

Input power = 1.2 × 10⁹ / 0.30 =  4  × 10⁹ W

Energy =  4  × 10⁹ x 60 x 60 = 1.44 x 10¹³ joules

E = m c² , where c is the speed of light and m is the mass.

⇒ mass = m = E / c²  = (1.44 x 10¹³) / (3 × 10⁸ )²

                                   = 0.00016 kg

6 0
4 years ago
A capacitor is formed from two concentric spherical conducting shells separated by vacuum. The inner sphere has radius 11.0 cm ,
viktelen [127]
Part A)
First of all, let's convert the radii of the inner and the outer sphere:
r_A = 11.0 cm = 0.110 m
r_B = 16.5 cm=0.165 m
The capacitance of a spherical capacitor which consist of two shells with radius rA and rB is
C=4 \pi \epsilon _0  \frac{r_A r_B}{r_B- r_A}=4\pi(8.85 \cdot 10^{-12}C^2m^{-2}N^{-1}) \frac{(0.110m)(0.165m)}{0.165m-0.110m}=
=3.67\cdot 10^{-11}F

Then, from the usual relationship between capacitance and voltage, we can find the charge Q on each sphere of the capacitor:
Q=CV=(3.67\cdot 10^{-11}F)(100 V)=3.67\cdot 10^{-9}C

Now, we can find the electric field at any point r located between the two spheres, by using Gauss theorem:
E\cdot (4 \pi r^2) =  \frac{Q}{\epsilon _0}
from which
E(r) =  \frac{Q}{4 \pi \epsilon_0 r^2}
In part A of the problem, we want to find the electric field at r=11.1 cm=0.111 m. Substituting this number into the previous formula, we get
E(0.111m)=2680 N/C

And so, the energy density at r=0.111 m is
U= \frac{1}{2} \epsilon _0 E^2 =  \frac{1}{2} (8.85\cdot 10^{-12}C^2m^{-2}N^{-1})(2680 N/C)^2=3.17 \cdot 10^{-5}J/m^3

Part B) The solution of this part is the same as part A), since we already know the charge of the capacitor: Q=3.67 \cdot 10^{-9}C. We just need to calculate the electric field E at a different value of r: r=16.4 cm=0.164 m, so
E(0.164 m)= \frac{Q}{4 \pi \epsilon_0 r^2}=1228 N/C

And therefore, the energy density at this distance from the center is
U= \frac{1}{2}\epsilon_0 E^2 =  \frac{1}{2} (8.85\cdot 10^{-12}C^2m^{-2}N^{-1})(1228 N/C)^2=6.68 \cdot 10^{-6}J/m^3
8 0
3 years ago
An equipoterntial surface that surrounds a + 3.0 pC point charge has a radius of 2.0 cm. What is the potential of this surface?​
mestny [16]

Answer:

Electric potential = 0.00054 V

Explanation:

We are given;

Charge; q = 3 pC = 3 × 10^(-12) C

Radius; r = 2 cm = 0.02 m

Formula for the electric potential of this surface will be;

V = kqr

Where;

K is a constant = 9 × 10^(9) N⋅m²/C².

Thus;

V = 9 × 10^(9) × 3 × 10^(-12) × 0.02

V = 0.00054 V

8 0
3 years ago
Which type of macromolecules a cell brake down food?
kobusy [5.1K]

Answer:

Hope this helps you find the answer

Explanation:

The proteins, lipids, and polysaccharides that make up most of the food we eat must be broken down into smaller molecules before our cells can use them—either as a source of energy or as building blocks for other molecules.

8 0
3 years ago
Choose the letter of the best description of the nature of light:
Andreas93 [3]
C. Light sometimes behaves like waves and at other times like particles.
6 0
3 years ago
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