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natima [27]
3 years ago
14

Felipe drives his car at a velocity of 28 m/s. He applies the brake, which slows the vehicle down at a rate of 6.4 m/s2 and caus

es it to slow to a stop. How long does it take for the car to stop? Round your answer to the nearest tenth.
I'm supposed to use derived formulas to find the answer but I don't know which one to use.

Physics
2 answers:
zysi [14]3 years ago
6 0
So after ~4.4 seconds, car will stop.

EastWind [94]3 years ago
6 0
The answer is: 4.4 seconds
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A 38.2 kg wagon is towed up a hill inclined at 17.5 ◦ with respect to the horizontal. The tow rope is parallel to the incline an
Tema [17]

Answer:

v = 8.57 m/s

Explanation:

As we know that the wagon is pulled up by string system

So the net force on the wagon along the inclined is due to tension in the rope and component of weight along the inclined plane

So as per work energy theorem we know that

work done by tension force + work done by force of gravity = change in kinetic energy

F_t . d - (mgsin\theta)(d) = \frac{1}{2}mv^2 - 0

so we have

F_t = 129 N

\theta = 17.5^o

m = 38.2 kg

d = 85.4 m

so now we have

129(85.4) - (38.2)9.8sin17.5 (85.4) = \frac{1}{2}(38.2) v^2

v = 8.57 m/s

7 0
3 years ago
A meter stick is suspended vertically at a pivot point 22 cm from the top end. It is rotated on the pivot until it is horizontal
suter [353]

Answer:

5.82812 rad/s

Explanation:

L = Length of meter stick = 1 m = 100 cm

m_c = The center of mass of the stick = \frac{L}{2}-0.22=0.5-0.22=0.28\ m

\omega = Angular velocity

Moment of inertia of the system is given by

I=I_c+mr^2\\\Rightarrow I=\frac{mL^2}{12}+mr^2\\\Rightarrow I=\frac{m1^2}{12}+m0.28^2\\\Rightarrow I=m(\frac{1}{12}+0.0784)

As the energy in the system is conserved

mgh=I\frac{\omega^2}{2}\\\Rightarrow mgh=m(\frac{1}{12}+0.0784)\frac{\omega^2}{2}\\\Rightarrow gh=(\frac{1}{12}+0.0784)\frac{\omega^2}{2}\\\Rightarrow \omega=\sqrt{\frac{2gh}{\frac{1}{12}+0.0784}}\\\Rightarrow \omega=\sqrt{\frac{2\times 9.81\times 0.28}{\frac{1}{12}+0.0784}}\\\Rightarrow \omega=5.82812\ rad/s

The maximum angular velocity is 5.82812 rad/s

4 0
3 years ago
when the driver of a car applies the brakes a force of 4000N brings the car to a stop over a distance of 50m.calculate the work
Dimas [21]

Answer:

W = F*d

W = 4000*50

W = 200000J

W = 200KJ

4 0
3 years ago
The sum of the charges on both plates of a capacitor is zero. What does a capacitor store?
erma4kov [3.2K]

Current is the overall flow of electrons through a conductor and can be defined as the speed of the flow of electrons. Resistance is defined as the opposition to current flow. Circuits must have resistance  to convert electrical energy into light, heat, or motion. Resistance is called the directional movement of electrons that form an electric current. It is also known that  electrons do not move freely in the crystal structure of a conductor. Resistance is the inherent opposition to the flow of electrons present in a conductor. Inductance is the property of any circuit to resist any change in current while capacitance is the property of the circuit to resist any change in voltage.

<h3>What is capacitor?</h3>

A capacitor is an electronic component that stores an electrical charge. Capacitors consist of two close conductors (usually plates) separated by a dielectric material. The plates accumulate an electrical charge when connected to a power source. The main purpose of a capacitor is to store electrostatic energy in an electric field and, if possible, to supply this energy to an electrical circuit.

To avoid dangerous circuit failure, they allow alternating current to flow but block direct current. Capacitors are widely used as circuit elements in many common electrical devices. Commercial capacitors are made of interwoven metal foils with paraffin or Mylar-impregnated paper as the dielectric.

To more about capacitor, visit ;

brainly.com/question/14562804

#SPJ4

4 0
1 year ago
19. Explain why a magnet from your refrigerator could not be used to lift something as heavy as a car. (Chapter 7 – Pages 202-20
tangare [24]

19. Answer:

It is because the gravitational force of Earth on a car is much more than the magnetic force from a refrigerator magnet. The gravitational force of earth on an object is directly proportional to the mass of the object. Due to the large mass of the car. the gravitational force on it is much greater and a refrigerator magnet cannot be used to lift the car.

20. Answer:

No, a magnet can never have a single pole. When cut in half, it develops two poles again

This is explained by Gauss's law of magnetism according to which the divergence of magnetic field is zero. The magnetic field lines must form a closed loop. In order to form a balanced closed loop, a magnet must have two poles.

21. Answer:

If the frequency of a wave is increased, the wavelength decreases.

Let us assume a wave with velocity v and wavelength λ is moving with a frequency f. We know that the velocity of a wave is always constant and is given as:

v = fλ

or λ=v/f

the relationship between λ and f is given as:

λ ∝ 1/f

When frequency is increased, the wavelength decreases.

22. Answer:

Wavelength of an ocean wave = λ = 10 m

Frequency of the ocean wave = f = 4.0 Hz

Velocity of the wave = v = ?

We know that for a wave with wavelength λ and frequency f, the velocity of that wave is given by the formula:

                             v = fλ

Using the given values in the formula:

v = (4 Hz)(10 m)

v = (4 s⁻¹)(10 m)                     (f = 1/T and Hz = s⁻¹)

v = 40 ms⁻¹

23. Answer:

If the sound of a siren becomes lower in pitch, it means that the vehicle is moving away from you. This is because of Doppler's effect.

According to Doppler's effect, when the source is moving away from a stationary receiver, the wavelength of the wave increases and thus the frequency f of the wave decreases to frequency f'.

f' = f(V/(V + Vs)         (V = velocity of wave ;   Vs = Velocity of source)

24. Answer:

Two astronauts in space are unable to hear each other. This is because sound waves cannot travel in space.

Sound waves are longitudinal waves. They need a medium to travel. Sound travels to our year by vibrating through the air molecules. In deep space, there are no molecules to vibrate. So there is no sound.

25. Answer:

Electromagnetic waves can transfer energy through vacuum.

EM waves are produced from an oscillating charged particles. It contains electric field waves and magnetic field waves oscillating perpendicular to each other. The plane of propagation of EM wave is in a plane perpendicular to both of them.

Once in motion, EM waves are self-perpetuating. Change is one field produces the other and so on.

26. Answer:

Three types of electromagnetic waves:

Ultraviolet rays:

Waves that have wavelength just shorter than the visible rays. Example is the UV radiations from the sun that cause sunburns.

X-rays:

X-rays have wavelength even shorter than UV radiations. Example: X-rays are used to take pictures of bones. They can penetrate through skin and muscles.

Gamma rays:

Gamma rays are the shortest waves and have the most energy. Example: Gamma rays used in treating cancer.

27. Answer:

A leaf usually appears to be green because chlorophyll absorbs light in the red and the blue regions of the visible light spectrum. Green light is not absorbed but reflected, making the plant appear green. Similarly, A red flower appears red because it reflects wavelengths most strongly in the red part of the spectrum. Light in the other range is absorbed.

28. Answer:

Light waves have different speed in different mediums.

On reflection, it remains in the same medium. So the speed of light also remains constant.

In refraction, the medium changes and the speed changes as well. Light is slower in denser mediums. Velocity of the light wave will decrease in a denser medium. To keep frequency constant, the wavelength of the wave will also shorten.

29. Answer:

A Convex lens converges the light rays towards the principal axis. Where as a Concave lens diverges the light rays away from the principal axes.

Convex lens is thicker at the center while Concave lens is thinner at the center.

Convex lens has a positive focal length while the concave lens has a negative focal length.

30. Answer:

The mirror used in rear-view mirror of a car are slightly curved (convex mirror).

The mirror is curved in an attempt to eliminate blind spots for the driver, making it safer and easier to view objects on the back of the vehicle.

The warning, "Objects in mirror are closer than they appear." is important because it is true. The image formed by a convex mirror is far than that of the actual objects. So, the driver is warned.

6 0
3 years ago
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