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3 years ago

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A cyclist is riding his bike up a mountain trail. When he starts up the trail, he is going 8 m/s. As the trail gets steeper, he

slows to 3 m/s in 1 minute. What is the cyclist's acceleration?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 causes it to slow to a stop. How long does it take for the car to stop? Round your answer to the nearest tenth.

1 answer:

shusha [124]3 years ago

3 0

Answer:

a) a = - 0.0833 m / s², b) t = 4.4 s

Explanation:

a) this is a kinematics exercise where the acceleration is along the inclined plane

v = v₀ - a t

a = v₀ - v / t

a = 3 - 8/60

a = - 0.0833 m / s²

b) in this case the final velocity is zero

v = v₀ - a t

0 = v₀ - at

t = v₀ / a

t = 28 / 6.4

t = 4.375 s

t = 4.4 s

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A solenoidal coil with 21 turns of wire is wound tightly around another coil with 350 turns. The inner solenoid is 22.0 cm long

Thepotemich [5.8K]

Answer:

(a)The average of magnetic flux trough each turns is $3.63 \times 10^{-8}$ wb.

(b) The magnitude of mutual inductance of the two solenoid is $1.596 \times 10^{-5}$ H.

(c)The magnitude of emf induced in the outer solenoid by changing current in the inner solenoid is 0.027132 v .

Explanation:

Given that,

The number of turns of the solenoid=N₁= 350

The diameter of the solenoid=D= 2.20 cm=0.022

The length of the solenoid is = $l$ = 22.0 cm=0.22 m

The second solenoid with $N_2$ = 21 turns which is wound around the solenoid at its center.

The current in the inner solenoid is $I_1$ = 0.150 A and is increasing at a rate of 1700 A/s i.e $\frac{dI_1}{dt}= 1700$ A/s

(a)

The formula of magnetic field of a solenoid is

$B=\mu_0 nI=\frac{\mu_0 N_1I_1}{l}$

$=\frac{(4\pi \times 10^{-7} T.m/A) (350)(0.15 \ A)}{0.220 \ m}$

$\approx 3.0 \times 10^{-4}$ T

So, the magnetic flux of each turns

$\phi = BA=B \pi (\frac d2)^2$

$=(3.0\times 10^{-4}\ T)\pi (\frac {0.022}{2} \ m)^2$

$=1.14 \times 10^{-7}$ wb

The average of magnetic flux trough each turns is $3.63 \times 10^{-8}$ wb.

(b)

Since the both coil wound tightly. So, the magnitude magnetic flux though each turns of both coils is same.

The mutual inductance of the two solenoid is

$M=\frac{N_2\phi}{I_1}$

$=\frac{(21)(1.14 \times 10^{-7}\ wb)}{0.15\ A}$

$=1.596 \times 10^{-5}$ H

(c)

The formula of emf is

$\varepsilon =-M\frac{dI_1}{dt}$

$=-(1.596\times 10^{-5}\ H) (1700 \ A/s)$

$=27.132 \times 10^{-3}$ v

=0.027132 v

The emf induced in the outer solenoid by changing current in the inner solenoid is 0.027132 v .

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3 years ago

Identify the forces acting on motor vehicle in straight line motion on a horizontal surface

tigry1 [53]

Friction, engine thrust, normal reaction and weight, these are the forces acting on motor when it moves in a straight line

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3 years ago

.A 0.2-kg aluminum plate, initially at 20°C, slides down a 15-m-long surface, inclined at a 30 angle to the horizontal. The forc

Ainat [17]

To solve this problem, it is necessary to apply the concepts related to Work according to the Force and distance, as well as the concepts related to energy lost-or gained-by heat. Mathematically the energy corresponding to heat is given as:

$Q = mC_p(\Delta T)$

Where,

m = mass

$C_p$ = Specific heat

$\Delta T$ = Change in Temperature

At the same time the Work made by the Force and the distance is given as:

$W = F*d \rightarrow W=mg*d$

As the force is applied at an angle of 30 degrees, the efficient component would be given by the vertical then the work / energy would be determined as:

$W = mg*dsin(30)$

$W = (15m)(0.2kg)(9.81)(sin30)$

$W = 13.24J$

Now this energy is used to heat the aluminum. We can find the change at the temperature as follow:

$Q = mC_p(\Delta T)$

$13.24 = (0.2)(900)(\Delta T)$

$\Delta T = 0.0736 \°C$

Therefore the correct answer is B.

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3 years ago

PLS HELP BEING TIMED!!!

Elodia [21]

Answer:

$K_{i}+U_{g,i} = K_{f}+U_{g,f}$

Explanation:

A closed system is a system where exists energy interactions with surroundings, but not mass interactions. If we neglect any energy interactions from boundary work, heat, electricity, magnetism and nuclear phenomena and assume that process occurs at steady state and all effects from non-conservative forces can be neglected, then the equation of energy conservation is reduce to this form:

$\Delta K +\Delta U_{g} = 0$ (1)

Where:

$\Delta K$ - Change in kinetic energy of the system, measured in joules.

$\Delta U_{g}$ - Change in gravitational potential energy of the system, measured in joules.

If we know that $\Delta K=K_{i}-K_{f}$ and $\Delta U_{g} = U_{g,i}-U_{g,f}$ , then we get the following equation:

$K_{i}+U_{g,i} = K_{f}+U_{g,f}$ (2)

Where $i$ and $f$ stands for initial and final states of each energy component.

Hence, the right answer is $K_{i}+U_{g,i} = K_{f}+U_{g,f}$

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3 years ago

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the density of dead sea surface water is about 1.166 g/ml. how much mass, in grams, would 2 liters of this salty water have?

kogti [31]

<span>Density is a value for mass, such as kg, divided by a value for volume, such as m^3. Density is a physical property of a substance that represents the mass of that substance per unit volume. The mass of the salty water is calculated as follows:

Mass = 1.166 g/mL ( 2000 mL ) = 2332 g of salty water</span>

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3 years ago

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