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Luda [366]
1 year ago
10

A 77 kg student traveling in a car with a constant velocity has a kinetic energy of 1.7 104 J. What is the speedometer reading o

f the car in km/h? answer with:_____km/h
Physics
1 answer:
AVprozaik [17]1 year ago
7 0

ANSWER

75.65 km/h

EXPLANATION

Given:

• The student's mass, m = 77 kg

,

• The kinetic energy of the student in the car, KE = 1.7 x 10⁴ J

Find:

• The speed read in the speedometer of the car, which is the speed of the student, v (in km/h)

The kinetic energy of an object with mass m, traveling at a speed v, is,

KE=\frac{1}{2}mv^2

Solving for v,

v=\sqrt{\frac{2KE}{m}}

Replace the known values and solve,

v=\sqrt{\frac{2\cdot1.7\cdot10^4J}{77kg}}\approx21.013m/s

Note that because the kinetic energy is given in Joules - which is equivalent to kg*m²/s², the speed we found is in m/s. Now, knowing that there are 3600 seconds in 1 hour and that 1 km is equivalent to 1000 m, we can convert this to km/s,

v=21.013\frac{m}{s}\cdot\frac{3600s}{1h}\cdot\frac{1km}{1000m}\approx75.65km/h

Hence, the speedometer reading of the car is 75.65 km/h, rounded to the nearest hundredth.

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In an electricity experiment, a 1.10 g plastic ball is suspended on a 56.0 cm long string and given an electric charge. A charge
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T=\dfrac{mg}{\cos\theta}\\\\T=\dfrac{1.1\times 10^{-3}\times 9.8}{\cos(21)}\\\\T=0.0115\ N

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Three parallel wires each carry current I in the directions shown in (Figure 1). The separation between adjacent wires is d.
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(b) The magnitude of the net magnetic force per unit length on the middle wire is zero.

(c) The magnitude of the net magnetic force per unit length on the bottom wire is 3μI²/4πd.

<h3>Force per unit length</h3>

The magnitude of the net magnetic force per unit length on the top wire is calculated as follows;

F₁/L = (μI₁/2π) x (I₂/d + I₃/d)

F₁/L = (μI/2π) x (I/d + I/d)

F₁/L = (μI/2π) x (2I/d)

F₁/L = μI²/πd

The magnitude of the net magnetic force per unit length on the middle wire is calculated as follows;

F₂/L = (μI₂/2π) x (I₃/d - I₁/d)

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The magnitude of the net magnetic force per unit length on the middle bottom is calculated as follows;

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F₃/L =  (μI/2π) x (3I/2d)

F₃/L =  3μI²/4πd

Thus, the magnitude of the net magnetic force per unit length on the top wire is μI²/πd.

The magnitude of the net magnetic force per unit length on the middle wire is zero.

The magnitude of the net magnetic force per unit length on the bottom wire is 3μI²/4πd.

Learn more about magnetic force here: brainly.com/question/13277365

#SPJ1

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