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2 years ago

A 1250-kg car moves at 20.0 m/s. How much work must be done on the car to increase its speed to 30.0 m/s.

Physics

1 answer:

bulgar [2K]2 years ago

6 0

Answer:

312,497.5Joules

Explanation:

Work done = force × distance

W = FS

Get the force

F = ma

F = 1250×9.8

F = 12250N

Get the distances using the equation of motion

v² = u² +2gS

30² =20²+2(9.8)S

900 =400+19.6S

900-400 =19.6S

500 = 19.6S

S = 500/19.6

S = 25.51m

Get the work done

Work done = 12250×25.51

Workdone = 312,497.5Joules

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A low resistance light bulb and a high resistance light bulb are connected in parallel with each other. Which bulb is brighter i

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<h2>Answer:</h2>

The bulb with low resistance will be brighter.

<h2>Explanation:</h2>

The brightness of a bulb is a function of both the voltage across the bulb and current flowing through the bulb. The higher the voltage, the higher the current. Hence the brighter the bulb.

Now, according to the question, the bulbs (the high resistance bulb and the low resistance bulb) are connected in parallel with each other. This means that the same voltage passes across them.

Also, we know that according to Ohm's law, the voltage (V) and current (I) through a conductor are related by the following equation;

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Where;

R is the resistance of the conductor.

We can re-write equation (i) as follows;

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According to equation (ii), at fixed voltage (V), the current (I) will increase as the resistance (R) decreases.

Now, since the two bulbs have the same voltage, the bulb with the low resistance will allow a larger flow of current than the bulb with high resistance. Therefore, as said earlier that brightness is dependent on voltage and current, the bulb with the low resistance (and having larger current at some voltage) will be brighter than the bulb with the high resistance (having smaller current at same voltage).

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The force is -12,000 N

Explanation:

First of all, we calculate the acceleration of the ball, by using the following suvat equation:

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u = 40 m/s is the initial velocity

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s = 2.0 cm = 0.02 m is the displacement of the ball

Solving for a,

$a=\frac{v^2-u^2}{2s}=\frac{0-40^2}{2(0.02)}=-40,000 m/s^2$

Now we can calculate the average force exerted on the ball, by using Newton's second law:

$F=ma$

where

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Substituting,

$F=(0.3)(-40,000)=-12,000 N$

where the negative sign indicates that the direction of the force is opposite to the direction of motion of the ball.

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2 years ago

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Answer:

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5) changes the horizontal speed, should change range

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Explanation:

1) After reading your long writing, we are going to solve the exercise, in the attachment you can see the different vectors.

2) The acceleration vectors are vertical and directed downwards due to the attraction of the Earth (gravity force) this force is constant, on the x axis there is no acceleration

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v_y = v_{oy} - gt

at the point of maximum height, vy = 0 is equal to the maximum height

4) For someone to change the horizontal acceleration we must assume a friction with the air, in this case they relate it would be in the opposite direction to the horizontal speed

In the graph it would be directed to the left, therefore the velocity would be

vₓ = v₀ₓ - ax t

5 and 6) If someone changes the horizontal speed, they should change the range of the shot for greater horizontal speed, the rock goes further.

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x = v₀ₓ t

y = v_{oy} t - ½ g t²

7) If someone changes the vertical speed change the maximum height, but not the scope of the shot, for higher speed higher maximum height,

the equations of motion are the same.

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