As the motor speeds up, the value of current decreases because of A. Friction loss B. Increase in resistance C. Increase in back emf D. All mentioned above

Answer:

(a) The optimum banking Decreases

(b) The optimum banking Increases

(c) The optimum banking is approximately 86.88°

Explanation:

(a) The equation of motion on a banked road is given as follows;

[tex]v = \sqrt{R \cdot g \times \left(\dfrac{tan (\theta) + \mu}{1 - \mu \cdot tan (\theta) }\right) }[/tex]

For no friction, we have;

v = √(R·g·tan(θ))

Where;

R₁ = The radius of the road

g = The acceleration due to gravity ≈ 9.81 m/s² = Constant

θ₁ = The bank angle

μ = The coefficient pf friction = Constant

v = The vehicle's speed

If the radius doubles, for no friction, we have;

v² = R·g·(tan(θ))

tan(θ) = v²/(R·g)

Therefore, when the radius doubles, tan(θ) becomes smaller and therefore, the optimum banking angle θ decreases (becomes smaller)

(b) When the speed doubles, we have;

v₁ = 2·v

∴ tan(θ₁) = (v₁)²/(R·g) = 4·(v)²/(R·g) = 4·tan(θ)

When the speed doubles, tan(θ) increases and therefore, the optimum banking angle θ increases increases

(c) The radius negotiated by the car, R = 80 cm = 0.8 m

The speed of the car, v = 12 m/s

From tan(θ) = v²/(R·g), we have;

tan(θ) = 12²/(0.8 × 9.81) ≈ 18.349

θ ≈ arctan(18.349°) ≈ 86.88°

Answer:

1.25 m

Explanation:

From the question given above, the following data were obtained:

Force ratio = 2.5

Distance of load from the fulcrum = 0.5 m

Distance of effort =.?

The distance of the effort from the fulcrum can be obtained as illustrated below:

Force ratio = Distance of effort / Distance of load

2.5 = Distance of effort / 0.5

Cross multiply

Distance of effort = 2.5 × 0.5

Distance of effort = 1.25 m

Therefore, the distance of the effort from the fulcrum is 1.25 m

the order of vector addition doesn't affect the resultant vector and grouping or order of pair doesn't effect the sum.

Answer:

[tex]v=-4.93\times 10^{5}~m/s[/tex] [negative sign denotes that it is moving away]

Explanation:

Actual wavelength of hydrogen spectral lines, [tex]\lambda=121.6~nm[/tex]

Apparent wavelength of hydrogen spectral lines from a star, [tex]\lambda'=121.8~nm[/tex]

So, shift in wavelength:

[tex]\Delta \lambda=\lambda'-\lambda[/tex]

[tex]\Delta \lambda=121.8-121.6[/tex]

[tex]\Delta \lambda=0.2~nm[/tex]

Using Doppler's shift:

[tex]\frac{\Delta \lambda}{\lambda} =-\frac{v}{c}[/tex]

[tex]\frac{0.2}{121.6} =-\frac{v}{3\times 10^8}[/tex]

[tex]v=-4.93\times 10^{5}~m/s[/tex] [negative sign denotes that it is moving away]

The answer would be B..

Since sand can heat up quickly, it will also cool off quickly. But water takes a long time to heat up and cool down.

Answer:

U = - ∫ F dx

U = - 3F₀

Explanation:

Force and potential energy are related

         F = [tex]- \frac{dU}{dx}[/tex]

         dU = - F dx

        ∫ dU = - ∫ F dx

        U- U₀ = - ∫ F dx

to solve the problem we must know the form of the force, if we assume that F = F₀ and U₀ = 0 for x = 0

         U = - F₀ 3

Answer:

[tex]T=8.33A[/tex]

Explanation:

From the question we are told that:

Number of battery [tex]n=10[/tex]

Voltage source[tex]E=12V[/tex]

Lamp Power[tex]P=10W[/tex]

Generally the equation for Resistance is mathematically given by

 [tex]R=\frac{V^2}{P}[/tex]

 [tex]R=\frac{12^2}{10}[/tex]

 [tex]R=14.4ohms[/tex]

Therefore

 [tex]R_{eq}=\frac{14.4}{10}[/tex]

 [tex]R_{eq}=1.44[/tex]

Generally the equation for Current is mathematically given by

 [tex]T=\ffrac{V}{Req}[/tex]

 [tex]T=\frac{12}{1.44}[/tex]

 [tex]T=8.33A[/tex]

The amount of energy required for a unit mass of a substance to undergo a phase change from liquid to gas.

Speed = distance /  time

Speed = 12km /  5 minutes

Speed = 2.4 km per minute

Speed is measured per hour, 1 hour has 60 minutes.

2.4 km per minute x 60 minutes = 144 km per hour

Scalar quantity are physical quantities that have just magnitude, not direction.

Answer:

Explanation:

First job is to convert 72 km/hr to m/s:

[tex]72\frac{km}{hr}[/tex] × [tex]\frac{1000m}{1km}[/tex] × [tex]\frac{1hr}{3600s}[/tex] = 2.0 × 10¹ m/s

Now to find the acceleration which is

[tex]a=\frac{v_f-v_0}{t}[/tex] and filling in:

[tex]a=\frac{2.0*10^1-0}{11.5}=1.7\frac{m}{s^2}[/tex] That's part a. Part b want to know how far the car can get in 11.5 seconds (because that's the time it takes for the car to get to 72 km/hr). Since we know that the car can get 2.0 × 10¹ meters in 1 second, that means that in 11.5 seconds, the car can get 11.5(2.0 × 10¹) which is 230 meters.

Answer:

779.87 N/m²

Explanation:

Pressure = Force (F) / Area (A)

Recall :

Force = ma ; mass * acceleration due to gravity

a = 9.8 m/s² ; mass = 0.4kg

Force, F = 0.4 * 9.8 = 3.92 N

Area = πr² ; r = Radius = 4cm = 4 / 100 = 0.04 m

Area = π0.04² = 0.0050265 m²

Hence,

Pressure = 3.92 / 0.0050265

Pressure = 779.86670 N/m²

Pressure = 779.87 N/m²

Answer:

Negative ion

.................

Explanation:

Hey there!

Given;

Mass of one object (m1) = 250kg

Mass of another object (m2) = 400 kg

Distance (d) = 100 m

Gravitational constant (g) = 6.67*10^-11

Now;

[tex]f = \frac{g.m1.m2}{ {d}^{2} } [/tex]

Keep all values;

[tex]f = \frac{6.67 \times {10}^{ - 11} \times 250 \times 400}{ {(100)}^{2} } [/tex]

Simplify

[tex]f = \frac{6.67 \times {10}^{ - 11} {10}^{5} }{10000} [/tex]

[tex]f = \frac{6.67 \times {10}^{ - 6} }{10000} [/tex]

Therefore, gravitational force is 6.67*10^-10.

Hope it helps!

Answer:

-8.036 kV/m

Explanation:

The electric field E = -ΔV/Δx where ΔV = change in electric potential = V - V' where V = electric potential at x = 5.6 cm =  450 V and V' = electric potential at x = 0 cm, = 0 V . So, ΔV = V - V' = 450 V - 0 V = 450 V.

Δx = distance between the 0 V plate and the 450 V point = 5.6 cm = 0.056 m

So, E = -ΔV/Δx

Substituting the values of the variables into the equation, we have

E = -ΔV/Δx

E = -450 V/0.056 m

E = -8035.7 V/m

E = -8.0357 kV/m

E ≅ -8.036 kV/m

Since the electric field between two parallel conducting plates is constant, the electric field between the plates is E = -8.036 kV/m

Answer:

MA = 1.66, VR = 2,  Efficiency = 83.33%

Explanation:

Given the following

Load = 500N

Effort = 300N

Mechanical Advantage = Load/Effort

MA = 500/300

MA = 5/3 = 1.66

Velocity ratio is the number of pulleyc present in the block and tackle system. Since the pulley is a single movable pulley, then VR = 2

Efficiecncy n = MA/VR * 100%

n = 1.66/2 * 100

n = 166/2

n = 83.33%

Explanation:

distance travelled = average speed x time

                               =30m/s*100s

                                =3000m

Answer:

3000m

Explanation:

30m/s*100s

3000m

Answer:

4p

Explanation:

If you halve the volume the pressure will double as they are inversely proportional. If you double the temperature the particles have double the kinetic energy so the pressure will double again.

So:

p×2×2 = 4p

Answer:

P V = n R T

P2 V2 / (P1 V1) = T2 / T1

P2 = (T2 / T1) (V1 / V2)  P1   =   2 * 2 = 4

hope it is helpful to you

Answer:

2.8 hours

Explanation:

98 ÷ 35 = 2.8

Answer:

D. bacteria feeding on the large volume of carp feces depleted the oxygen

Explanation:

In the context, it is given that in a small farm pond, the owner added 20 grass carp and feed them with the abundant plants and algae that is found on her pond. The carp grew large after many years but one summer the owner found the grass carps along with other fishes were dead.

The most possible explanation for the dead of the fishes in the pond because the bacteria feeds on the carp feces which depletes the dissolved oxygen present in the water. Thus the fishes could not breathe and were finally dead.

Therefore, the correct option is (D).

Answer:

1. 45 m

2. 50 m/s

Explanation:

From the question given above, the following data were obtained:

Initial velocity (u) = 20 m/s

Time (t) = 3 s

1. Determination of the position (i.e height)

Time (t) = 3 s

Acceleration due to gravity (g) = 10 m/s²

Height (h) =?

h = ½gt²

h = ½ × 10 × 3²

h = 5 × 9

h = 45 m

2. Determination of the velocity.

Initial velocity (u) = 20 m/s

Time (t) = 3 s

Acceleration due to gravity (g) = 10 m/s²

Velocity (v) =?

v = u + gt

v = 20 + (10 × 3)

v = 20 + 30

v = 50 m/s

Answer:

8m in 1 second

480m = 1 hour

11,520m in one day

Explanation:

Hope this is helpful

Answer:

1kg = 1000g

67kg therefore would be equal to

67 x 1000 = 67,000g = 6.7 x 10⁴g.

Answer:

31,556,736 seconds

Explanation:

The period of Earth's orbit around the Sun, T = (365 + 1/4) days (three hundred and sixty five and a quarter days

The period of Earth's orbit around the Sun in seconds is given by converting, T = [tex]365\frac{1}{4} \, days[/tex] into seconds as follows;

There are 60 seconds per minute, 60 minutes in each hour, 24 hours within each day, therefore, we get;

T = [tex]365\frac{1}{4}[/tex]×60 sec/min × 60 min/hr. × 24hr/day = 31,556,736 seconds

Answer:

Make a nice powerpoint and think about the question

Explanation:

Its easier than you think :)

Answer:

Because Moon and Mars has no atmosphere.

Explanation:

Moon and Mars has no atmosphere, so there is no friction on the falling object due to the atmosphere. The speed of the falling object is more at Moon and Mars.

When a small object impact on the surface of moon or Mars with high speed, the size of crater is large than the earth as out earth has atmosphere.