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sleet_krkn [62]
3 years ago
13

A moving car has kinetic energy. If it speeds up until it is going four times faster than before, how much kinetic energy does i

t have in comparison?
Physics
1 answer:
Eva8 [605]3 years ago
7 0
<h2>Ratio of final kinetic energy to initial kinetic energy is 16.</h2>

Explanation:

Kinetic energy , KE = 0.5mv²

Here car speeds up to four times the initial speed, we need to find ratio of final kinetic energy to initial kinetic energy.

Final speed = 4 x Initial speed = 4v

Initial KE = 0.5mv²

Final KE = 0.5 x m x (4v)²

Final KE = 16 x 0.5 x m x v²

Final KE = 16 x Initial KE

Ratio of final kinetic energy to initial kinetic energy is 16.

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Why might an electromagnet be used to pick up old cars in junk yards?
s344n2d4d5 [400]
I think the correct answer would be that because electromagnets are powerful and can be turned off and on anytime. Electromagnet is a magnet in which the magnetic field is made by the electric current that is induced to the system.
5 0
3 years ago
Read 2 more answers
For a constant voltage, how is the resistance related to the current?
Aleksandr-060686 [28]

Answer:

Resistance is inversely proportional to current, so when the resistance doubles, the current is cut in half. Resistance is directly proportional to current, so when the resistance doubles, the current is cut in half.

8 0
2 years ago
In the photoelectric effect, a photon with an energy of 5.3 × 10–19 J strikes an electron in a metal. Of this energy, 3.6 × 10–1
valentina_108 [34]

Answer:

The velocity of the photo electron is 6.11\times 10^5\ m/s.

Explanation:

Given that,

Supplied energy, E_s=5.3\times 10^{-19}\ J

Minimum energy of the electron to escape from the metal, E_e=3.6\times 10^{-19}\ J

We need to find the velocity of the photo electron. The energy supplied by the photon is equal to the sum of minimum escape energy and the kinetic energy of the escaping electron. So,

5.3\times 10^{-19}\ J=3.6\times 10^{-19}\ J+K\\\\K=5.3\times 10^{-19}-3.6\times 10^{-19}\\\\K=1.7\times 10^{-19}\ J

The formula of kinetic energy is given by :

K=\dfrac{1}{2}mv^2\\\\v=\sqrt{\dfrac{2K}{m}} \\\\v=\sqrt{\dfrac{2\times 1.7\times 10^{-19}}{9.1\times 10^{-31}}} \\\\v=6.11\times 10^5\ m/s

So, the velocity of the photo electron is 6.11\times 10^5\ m/s.

4 0
3 years ago
A sailboat moves north for a distance of 10.00 km when blown by a wind from the exact south with a force of 5.00 x 10^4 n. how m
Nataliya [291]
Work is defined as the force times the distance which is mathematically expressed W = Fxd. The given force is 5x10^4 and the distance is 10000 m (the distance is converted as meter because Nm = J) the work done by the wind is W = 5x10^4 N (10000) = 500 x 10^6 Joules. I hope it answered your question
8 0
3 years ago
A student sits at rest on a piano stool that can rotate without friction. The moment of inertia of the student-stool system is 4
irina [24]

Here We can use principle of angular momentum conservation

Here as we know boy + projected mass system has no external torque

Since there is no torque so we can say the angular momentum is conserved

mvL = (I + mL^2)\omega

now we know that

m = 2 kg

v = 2.5 m/s

L = 0.35 m

I = 4.5 kg-m^2

now plug in all values in above equation

2\times 2.5 \times 0.35 = (4.5 + (2\times 0.35^2))\omega

1.75 = [4.5 + 0.245]\omega

1.75 = 4.745\omega

\omega = 0.37 rad/s

so the final angular speed will be 0.37 rad/s

4 0
3 years ago
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