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3 years ago

An object has a kinetic energy Ek. What happens to the kinetic energy if we:

1 answer:

3 0

The energy possessed by a body because of its motion, equal to one half the mass of the body times the square of its speed is called its kinetic energy.
K=
2
1

mv
2

When, v=2v,
K
′
=
2
1

m(2v)
2

K
′
=4×
2
1

mv
2

K
′
=4K
Hence, when velocity is doubled, kinetic energy becomes 4 times.

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Which statements about braking a car are true? A)The greater the kinetic energy of a car, the longer it takes for the car to sto

NikAS [45]

Answer:

option c

Explanation:

Kinetic energy is due to the speed of a body.

$K.E = \frac{1}{2}mv^2$

When speed is doubled, the kinetic energy is quadruple.

From third equation of motion, braking distance is also proportional to square of speed. Thus, when speed is doubled, the braking distance is quadruple.

Thus, option c is correct.

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3 years ago

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A 10-turn coil of wire having a diameter of 1.0 cm and a resistance of 0.50 Ω is in a 1.0 mT magnetic field, with the coil orien

n200080 [17]

Answer:

The voltage across the capacitor is 1.57 V.

Explanation:

Given that,

Number of turns = 10

Diameter = 1.0 cm

Resistance = 0.50 Ω

Capacitor = 1.0μ F

Magnetic field = 1.0 mT

We need to calculate the flux

Using formula of flux

$\phi=NBA$

Put the value into the formula

$\phi=10\times1.0\times10^{-3}\times\pi\times(0.5\times10^{-2})^2$

$\phi=7.85\times10^{-7}\ Tm^2$

We need to calculate the induced emf

Using formula of induced emf

$\epsilon=\dfrac{d\phi}{dt}$

Put the value into the formula

$\epsilon=\dfrac{7.85\times10^{-7}}{dt}$

Put the value of emf from ohm's law

$\epsilon =IR$

$IR=\dfrac{7.85\times10^{-7}}{dt}$

$Idt=\dfrac{7.85\times10^{-7}}{R}$

$Idt=\dfrac{7.85\times10^{-7}}{0.50}$

$Idt=0.00000157=1.57\times10^{-6}\ C$

We know that,

$Idt=dq$

$dq=1.57\times10^{-6}\ C$

We need to calculate the voltage across the capacitor

Using formula of charge

$dq=C dV$

$dV=\dfrac{dq}{C}$

Put the value into the formula

$dV=\dfrac{1.57\times10^{-6}}{1.0\times10^{-6}}$

$dV=1.57\ V$

Hence, The voltage across the capacitor is 1.57 V.

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3 years ago

Which statement best describes the energy changes that occur while a child is riding on a sled down a steep, snow-covered hill?

svp [43]

The answer is C, because they moved from a stand still to down the hill

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4 years ago

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Zarrin [17]

Follow stop drop and roll if the fire is in the room
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patriot [66]

Answer:

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