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elixir [45]
3 years ago
8

A constant force is exerted on a cart that is initially at rest on a frictionless air track. The force acts for a short time int

erval and gives the cart a final speed. To reach the same speed using a force that is half as big, the force must be exerted for a time interval that is
Physics
1 answer:
Inessa05 [86]3 years ago
3 0

Let <em>F</em> be the magnitude of the force applied to the cart, <em>m</em> the mass of the cart, and <em>a</em> the acceleration it undergoes. After time <em>t</em>, the cart accelerates from rest <em>v</em>₀ = 0 to a final velocity <em>v</em>. By Newton's second law, the first push applies an acceleration of

<em>F</em> = <em>m a</em>   →   <em>a</em> = <em>F </em>/ <em>m</em>

so that the cart's final speed is

<em>v</em> = <em>v</em>₀ + <em>a</em> <em>t</em>

<em>v</em> = (<em>F</em> / <em>m</em>) <em>t</em>

<em />

If we force is halved, so is the accleration:

<em>a</em> = <em>F</em> / <em>m</em>   →   <em>a</em>/2 = <em>F</em> / (2<em>m</em>)

So, in order to get the cart up to the same speed <em>v</em> as before, you need to double the time interval <em>t</em> to 2<em>t</em>, since that would give

(<em>F</em> / (2<em>m</em>)) (2<em>t</em>) = (<em>F</em> / <em>m</em>) <em>t</em> = <em>v</em>

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Two bulbs marked 200 W-250 V and 100 W-250 V are joined in
lozanna [386]

Answer:

<em>P = 66.67 W</em>

Explanation:

<u>Joule Heating</u>

It's the process by which the electric current passing through a conductor produces heat.

Also known as Joule's first law or the Joule–Lenz law, states that the power of heating generated by an electrical conductor (P) is proportional to the product of its resistance (R) and the square of the current (I).

It can be described by the equation that follows:

P = I^2.R

Also, we can calculate the voltage V with the formula of Ohm's law:

V = I.R

Combining both equations, power can be related to the voltage:

\displaystyle P=\frac{V^2}{R}

Given the power and the voltage, the resistance can be calculated by solving for R:

\displaystyle R=\frac{V^2}{P}

There are two bulbs marked P=200W V=250V and P=100 W V=250.

The first bulb has a resistance of:

\displaystyle R_1=\frac{250^2}{200}

\displaystyle R_1=312.5\Omega

The first bulb has a resistance of:

\displaystyle R_2=\frac{250^2}{100}

\displaystyle R_1=625\Omega

When connected in series, the total resistance is

R = R_1 + R_2=312.5\Omega+625\Omega

R=937.5\Omega

The total power consumed when connecting them to a V=250 V supply is:

\displaystyle P=\frac{250^2}{937.5}

P = 66.67 W

4 0
3 years ago
A 5.00-kg object is hung from the bottom end of a vertical spring fastened to an overhead beam. The object is set into vertical
mezya [45]

Answer:A7.50kg object is hung from the bottom end of a vertical spring fastened to an overhead beam. The object is set into vertical oscillations having a period of2.30s. Find the force constant of the spring.

N/m

Explanation:

5 0
3 years ago
State the<br>the properties of magnets.<br>​
Zigmanuir [339]

Answer:

All magnets have two poles: the North Pole and the South Pole.

Magnets attract ferromagnetic materials such as iron, nickel, and cobalt.

The magnetic force of a magnet is stronger at its poles than in the middle.

A freely suspended magnet always points in North-South direction.

Hope this helps

4 0
3 years ago
A ball is released from rest at a height of 10 m and falls freely to the
ElenaW [278]

Answer:

The new kinetic energy would be 16 times greater than before.

Explanation:

Kinetic energy is found using this formula:

  • KE = 1/2mv²
  • where KE = kinetic energy (J), m = mass (kg), and v = velocity (m/s)

We can see that kinetic energy is directly proportional to the square of the velocity, meaning that if the speed was increased by 4 times, then the kinetic energy would get increased by a factor of 16.

The velocity just before the ball hits the ground can be found by the equation:

  • √(2gh)

Let's substitute h = 10 m and h = 40 m into this formula.

  • √(2g(10))
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We can see that the velocity increases by a factor of 4 (10 m → 40 m).

Therefore, this means that the kinetic energy would also be increased by a factor of (4)² = 16. Thus, the answer is D) The new kinetic energy would be 16 times greater than before.

6 0
3 years ago
Find the magnitude of the gravitational force exerted on a 66.5 kg astronaut on the surface of Planet X if the planet has a radi
pav-90 [236]
The correct formula to use is: F = G [M1*M2] /r^2
Where,
G = the force of gravity
M1 = the mass of the first object [the mass of the astronaut]
M2 = the mass of the second object [the mass of the planet]
r = the distance between the two objects in metre
F = 6.67 * 10^-11 [66.5 * 8.43 * 10^23] / [4.40 * 10^6]^2
F = 193N.<span />
8 0
4 years ago
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