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bekas [8.4K]
3 years ago
13

A small 18 kilogram canoe is floating downriver at a speed of 1 m/s. What is the canoe's kinetic energy?

Physics
1 answer:
In-s [12.5K]3 years ago
8 0

Kinetic energy = (1/2) (mass) (speed²).

A Physicist in the canoe, or on a raft floating downriver next to the canoe, will say that the canoe's kinetic energy is zero.

A Physicist on the riverbank, watching the canoe drift by at 1 m/s, will say that its kinetic energy is 9 Joules.

They're both correct.

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17 copper wires of length l and diameter d are connected in parallel to form a single composite conductor of resistance R. What
Lubov Fominskaja [6]

Answer:

\frac{D}{d} = 4.12

Explanation:

As we know that resistance of one copper wire is given as

r = \rho \frac{L}{a}

here we know that

a = \pi (\frac{d}{2})^2

now we have

r = \rho \frac{L}{\pi (\frac{d^2}{4})}

r = \rho \frac{4L}{\pi d^2}

now we know that such 17 resistors are connected in parallel so we have

R = \frac{r}{17}

R = \rho \frac{4L}{17 \pi d^2}

Now if a single copper wire has same resistance then its diameter is D and it is given as

R = \rho \frac{4L}{\pi D^2}

now from above two equations we have

\rho \frac{4L}{\pi D^2} = \rho \frac{4L}{17 \pi d^2}

D^2 = 17 d^2

now we have

\frac{D}{d} = 4.12

3 0
3 years ago
Poor measurement practices are likely to lead to data that are.....
zhannawk [14.2K]
Inconsistent. You should take three readings at least.
8 0
3 years ago
Read 2 more answers
What are the similarities and differences between novae and supernovae?
DochEvi [55]

Answer:

Explanation:

A novae in astronomy means an explosion in the white dwarf star which had tapped enough gas from a companion star,hence it releases an incredible amount of energy which is Over a million times brighter than it normal stars.

A super novae on the other hand is a cosmic explosion that can be a billion times brighter than the normal.

From this one can see that a perculiar similarity between a novae and super novae is that both generate huge explosion and bright Ness, and a major difference is super novae release huge amount of brightness and energy more than the novae

3 0
3 years ago
The sum of the charges on both plates of a capacitor is zero. What does a capacitor store?
erma4kov [3.2K]

Current is the overall flow of electrons through a conductor and can be defined as the speed of the flow of electrons. Resistance is defined as the opposition to current flow. Circuits must have resistance  to convert electrical energy into light, heat, or motion. Resistance is called the directional movement of electrons that form an electric current. It is also known that  electrons do not move freely in the crystal structure of a conductor. Resistance is the inherent opposition to the flow of electrons present in a conductor. Inductance is the property of any circuit to resist any change in current while capacitance is the property of the circuit to resist any change in voltage.

<h3>What is capacitor?</h3>

A capacitor is an electronic component that stores an electrical charge. Capacitors consist of two close conductors (usually plates) separated by a dielectric material. The plates accumulate an electrical charge when connected to a power source. The main purpose of a capacitor is to store electrostatic energy in an electric field and, if possible, to supply this energy to an electrical circuit.

To avoid dangerous circuit failure, they allow alternating current to flow but block direct current. Capacitors are widely used as circuit elements in many common electrical devices. Commercial capacitors are made of interwoven metal foils with paraffin or Mylar-impregnated paper as the dielectric.

To more about capacitor, visit ;

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4 0
1 year ago
0.180-kg stone rets on a frictionless, horizontal surface. A bullet of mass 7.50 g, traveling horizontally at 390 m/s, strikes t
Musya8 [376]

Answer:

The magnitud of the velocity is

8.46m/s

and the direccion:

-28.3 degrees from the horizontal.

Explanation:

Fist we define our variables:

m_{s}=0.18kg\\m_{b}=7.5g = 0.0075kg\\v_{1b}= 390m/s -i\\v_{1s}=0m/s\\v_{2b}=210m/s -j\\v_{2s}=?

The letters i and j represent the direction of the movement, i in this case is the horizontal direction, and j is perpendicular to i.

velocities with sub-index 1 are the speeds before the crash, and with sub-index 2 are the velocities after the crash.

Using conservation of momentum:

m_{s}v_{1s}+m_{b}v_{1b}=m_{s}v_{2s}+m_{b}v_{2b}\\v_{1s}=0, so\\m_{b}v_{1b}=m_{s}v_{2s}+m_{b}v_{2b}

Clearing for the velocity of the stone after the crash:

v_{2s}=\frac{m_{b}v_{1b}-m_{b}v_{2b}}{m_{s}}

Substituting known values:

v_{2s}=\frac{0.0075kg(((390m/s-i)-210m/s-j)}{0.18kg}\\v_{2s}=(16.25m/s-i) - (8.75m/s-j)

The magnitud of the velocity is :

|v_{2s}|=\sqrt{(16.25m/s-i)^2 + (8.75m/s-j)^2}\\|v_{2s}|=18.46m/s

and the direction:

tan^{-1}(-8.75/16.25)=-28.3

this is -28.3 degrees from the +i direction or the horizontal direcction.

Note: i and j can also be seen as x and y axis.

3 0
4 years ago
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