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3 years ago

Give three practical uses of electromagnets

1 answer:

7 0

Three practical uses of electromagnets would be
Light. The waves
Electric locks. The bolts that are used by the
coils
Cranes. The electric ones that are found in
scraps
Cars computers washing machines all use
Electromagnets . Even CD players DVDs
Players

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A wave has a frequency of 875 hz and a wavelength of 352 m. At what speed is this wave traveling

Sonbull [250]

Answer:

308,000 or 30.8×10^3

Explanation:

v=f×lamda

v is ?, f is 875Hz, lamda is 352m

v=875×352

v=308,000

v=30.8×10^3 m/s

5 0

3 years ago

How to derive the fourth equation of motion?

Leya [2.2K]

Answer:

To derive the fourth equation of motion, first we have to consider the equation for acceleration and then to rearrange it. or v2 = u2 + 2as and this equation of motion can be used to find the final velocity or the distance travelled if the other values are given.

Explanation:

v= u + at

s =( u + v ) t /2

s = ut + at2/2

v2 = u2 + 2as

6 0

3 years ago

An automobile engine can produce 153 N · m of torque. Calculate the angular acceleration (in rad/s^2) produced if 85.2% of this

galina1969 [7]

Answer:

46.2 rad/s2

Explanation:

Angular acceleration works very similar to linear acceleration, it follows this equation:

$\gamma = \frac{Mt}{J}$

Where:

γ: angular acceleration

Mt: torque

J: moment of inertia of the load from its turning axis

Since we have the torque we just need the moment of inertia. We have to add together the moments of the drive shaft, tires, wheel walls and wheels.

The wheels act like disks. For disks the moment of inertia is:

$J = \frac{1}{2} * m * r^2$

$Jwheel = \frac{1}{2} = 15 * 0.18^2 = 0.243 kg*m^2$

The wheel walls act like annular rings, for these the moment of inertia is:

$J = \frac{1}{2} * m * (re^2 - ri^2)$

$Jwall = \frac{1}{2} * 2 * (0.32^2 - 0.18^2) = 0.07 kg * m^2$

The tread acts like a hoop, as in mass concentrated into a circunference, for these:

$J = m * r^2$

$Jtread = 10 * 0.33^2 = 1.09 kg*m^2$

The axle acts like a rod, which is the same as the disk:

$Jaxle = \frac{1}{2} * 14.1 * 0.02^2 = 0.0028 kg*m^2$

The drive shaft acts like a rod too:

$Jshaft = \frac{1}{2} * 31.7 * 0.032^2 = 0.016 kg*m^2$

SO, the total moment of inertia is:

J = 2*Jwheel + 2*Jwall + 2*Jtread + Jaxle + Jshaft

J = 2*0.243 + 2*0.07 + 2*1.09 + 0.0028 + 0.016 = 2.82 kg*m2

Finally the angular acceleration is:

$\gamma = \frac{0.852 * 153}{2.82} = 46.2 \frac{rad}{s^2}$

4 0

3 years ago

To make ice, a freezer that is a reverse Carnot engine extracts 37 kJ as heat at -17°C during each cycle, with coefficient of pe

Dvinal [7]

Answer:

a) 6.4 kJ

b) 43.4 kJ

Explanation:

$Q_{a}$ = Heat absorbed = 37 kJ

$β$ = Coefficient of performance = 5.8

$W$ = Work done

Heat absorbed is given as

$Q_{a}$ = $β$ $W$

37 = (5.8) $W$

$W$ = 6.4 kJ

$Q$ = work per cycle required

$Q$ = $Q_{a}$ + $W$

$Q$ = 37 + 6.4

$Q$ = 43.4 kJ

5 0

3 years ago

The wavelength of a water wave is 6 cm when the frequency is 10 hertz .

dedylja [7]

The distance between successive crests (or successive troughs) is defined as the wavelength. The time elapsed between the crossings of two successive crests through a given point is the period of the wave.
The Velocity of propagation (Vp) of a cable is the speed at which an electrical signal can propagate through the cable in comparison to the speed of light. For example, in a vacuum, the velocity of propagation would be 100% or 1 (depending on how it is represented).
The wave period is the time it takes to complete one cycle. The standard unit of a wave period is in seconds, and it is inversely proportional to the frequency of a wave, which is the number of cycles of waves that occur in one second.

4 0

2 years ago