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3 years ago

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If the speed of a car is increased by 80%, by what factor will its minimum braking distance be increased, assuming all else is t

he same? Ignore the driver's reaction time.

1 answer:

Vikki [24]3 years ago

6 0

Answer:

$KE_2=3.24 \times KE_1$

Explanation:

given,

Speed of car = v

new speed of car v'= 1.8 v

Kinetic energy of the car

$KE_1 =\dfrac{1}{2}mv^2$

new Kinetic energy of energy

$KE_2 =\dfrac{1}{2}mv'^2$

$KE_2=\dfrac{1}{2}m(1.8v)^2$

$KE_2=3.24 \times \dfrac{1}{2}mv^2$

$KE_2=3.24 \times KE_1$

hence, the kinetic energy is increased by the factor of 3.24.

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ludmilkaskok [199]

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Art [367]

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2 years ago

A football is kicked from the ground with a velocity of 38m/s at an angle of 40 degrees and eventually lands at the same height.

Anastasy [175]

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Converting back to direction and magnitude, we get $\langle r,\theta \rangle=\langle \sqrt{29.11^2+24.23^2},tan^{-1}(\frac{29.11}{24.23}) \rangle = \langle 37.87,50.2^{\circ}\rangle$

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2 years ago

The filament of a certain lamp has a resistance that increases linearly with temperature. When a constant voltage is switched on

alekssr [168]

Answer:

The change in temperature is $\Delta T = 1795 K$

Explanation:

From the question we are told that

The temperature coefficient is $\alpha = 4 * 10^{-3 }\ k^{-1 }$

The resistance of the filament is mathematically represented as

$R = R_o [1 + \alpha \Delta T]$

Where $R_o$ is the initial resistance

Making the change in temperature the subject of the formula

$\Delta T = \frac{1}{\alpha } [\frac{R}{R_o} - 1 ]$

Now from ohm law

$I = \frac{V}{R}$

This implies that current varies inversely with current so

$\frac{R}{R_o} = \frac{I_o}{I}$

Substituting this we have

$\Delta T = \frac{1}{\alpha } [\frac{I_o}{I} - 1 ]$

From the question we are told that

$I = \frac{I_o}{8}$

Substituting this we have

$\Delta T = \frac{1}{\alpha } [\frac{I_o}{\frac{I_o}{8} } - 1 ]$

=> $\Delta T = \frac{1}{3.9 * 10^{-3}} (8 -1 )$

$\Delta T = 1795 K$

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3 years ago

A proton traveling due north enters a region that contains both a magnetic field and an electric field. The electric field lines

Bess [88]

Answer:

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Explanation:

In the electromagnetic system of force if the direction of motion of proton does not changes it means that the electric and magnetic forces are such a ways that they are cancelling each other's effect.

Since, electric field lines will exert a force on the proton to the west, hence, the magnetic force must force it to the east. It is well known that magnetic force acts perpendicular to the direction of magnetic field. magnetic field should point upward direction.

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2 years ago