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3 years ago

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5. A bus starting from rest accelerates in a straight line at a constant rate of 3m/s2 for 8s. Calculate the distance travelled

by the bus during this time interval.

1 answer:

mojhsa [17]3 years ago

8 0

Answer:

d = 96 meters

Explanation:

a = acceleration

t = time

d = distance

$d = \frac{1}{2} \times a \times {t}^{2}$

$d = \frac{1}{2} \times 3 \times {8}^{2}$

$d = 96$

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2) Why do you think fossil fueled cars are still out numbering alternative and replacement fueled cars even though fossil fuels

Misha Larkins [42]

Answer:

Fossil-fueled cars are still outnumbering the alternative and replacement-fueled cars because they are generally cost-effective and are efficient.

Explanation:

<em>Fossil fuels</em> are non-renewable energy that cannot be replenished. Although many people know how harmful using them can be to the environment, still, people continue to buy cars that are powered by it. This is because, <em>using fossil-fueled cars can help you save money</em> compared to using<em> replacement-fueled cars.</em><em> Its engines are also more powerful,</em> which means they can arrive at their destination in just a few minutes. <u>This makes it efficient.</u> The cost of maintaining a fossil-fueled car is less expensive compared to<em> replacement-fueled cars.</em> People are naturally keen when it comes to budgeting, thus, many people still buy cars powered by fossil fuels.

3 0

2 years ago

Endothermic reactions give off heat as they proceed. <br> a. True<br> b. False

Temka [501]

B. False
Endothermic reactions absorb heat.

5 0

3 years ago

Ksju [112]

1. False

Explanation: it's exactly the opposite. In fact, Lenz's law states that the induced current and the induced emf in a conductor are generated in such a direction that opposes to the change in magnetic flux through the coil. This is summarized by the negative sign in the Faraday's Newmann Lenz law:

$\epsilon= -\frac{d\Phi }{dt}$

where $\epsilon$ is the emf induced and $\frac{d\Phi}{dt}$ is the rate of change of magnetic flux through the coil.

Lenz's law is a consequence of the law of conservation of energy. In fact, we have:

- If the magnetic flux through a coil is increasing, then the induced current has a direction such that the magnetic field generated by the coil is opposite to the direction of the external magnetic field, in order to decrease the total flux

- If the magnetic flux through a coil is decreasing, then the induced current has a direction such that the magnetic field generated by the coil is in the same direction as the external field, in order to increase the total flux

2. False

Explanation: the magnetic flux through a surface is given by

$\Phi = BA cos \theta$

where

B is the magnitude of the magnetic field

A is the surface area

$\theta$ is the angle between the direction of B and the normal vector to the surface

As we see, the magnetic flux depends not only on B and A, but also on the orientation of the coil with respect to the magnetic field.

3. False

Explanation:

- Sound waves are mechanical waves: mechanical waves are waves consisting of oscillations of the particles in a medium. Due to their nature, therefore, mechanical waves can propagate only in the presence of a medium

- Electromagnetic waves are NOT mechanical waves: they consist of oscillations of electric and magnetic fields, in a direction perpendicular to the direction of propagation of the wave. Since em waves are not mechanical waves, they do NOT need a medium to propagate, since they can also travel through a vacuum; therefore the original statement is false.

5 0

2 years ago

Two planets having equal masses are in circular orbit around a star. Planet A has a smaller orbital radius than planet B. Which

vova2212 [387]

Answer:

Explanation:

To solve this, we must know two things.

First, the force of gravity acting on an orbiting object is equal to its mass times centripetal acceleration.

Second, the force of gravity between two objects is defined by Newton's law of universal gravitation: Fg = mMG/r², where Fg is the force of gravity, m and M are the masses of the objects, G is the universal constant of gravitation, and r is the distance between the objects.

Therefore:

Fg = m v²/r

mMG/r² = m v²/r

v² = MG/r

The potential energy of each planet is:

PE = mgr = m (MG/r²) r = mMG/r

The kinetic energy of each planet is:

KE = 1/2 mv² = 1/2 m (MG/r) = 1/2 mMG/r

The total mechanical energy is:

ME = PE + KE = 3/2 mMG/r

Since both planets have the same mass, the only difference is the orbital radius. Since planet A has a smaller orbital radius, it has more potential energy, more kinetic energy, and more mechanical energy.

6 0

2 years ago

A non-ideal 12.2 V battery is connected across a resistor R. The internal resistance of the battery is 1.9Ohm. Calculate the pot

Brums [2.3K]

Answer:

R=100 Ohm, V=11.97 volts and I=0.12 amperes

R=10 Ohm, V=10.25 volts and I=1.20 amperes

R=2 Ohm, V=6.26 volts

Explanation:

The potential difference (voltage) of a battery with internal resistance is:

$V=\xi-Ir$ (1)

with $\xi$ the electromotive force (the voltage the batteries say to has) , I the current and r the internal resistance. By Ohm's law the current that passes through the resistor is:

$I=\frac{V}{R}$ (2)

using (2) on (1):

$V=\xi-\frac{V*r}{R}$

solving for V:

$V+\frac{V*r}{R}=\xi$

$V=\frac{\xi}{1+\frac{r}{R}}$ (3)

R=100 Ohm

$V=\frac{12.2}{1+\frac{1.9}{100}}=11.97 V$

R=10 Ohm

$V=\frac{12.2}{1+\frac{1.9}{10}}=10.25 V$

R=2 Ohm

$V=\frac{12.2}{1+\frac{1.9}{2}}=6.26 V$

Because we have now the values of I on the circuit (is the same through all the components because is a series circuit)

We use back substitution on (1) to find the current:

R=100 Ohm

$I=\frac{V}{R}=\frac{11.97}{100}=0.12 A$

R=10 Ohm

$I=\frac{V}{R}=\frac{11.97}{10}=1.20 A$

7 0

3 years ago