Gravity does not actually "pull" objects at

BLANK causes movement of an object, whereas BLANK is the work done on an object in a given amount of time.

Setler [38]

The first one is Force & the second one Power.

3 0

3 years ago

Read 2 more answers

A certain car can accelerate from 0 to 60 mph in 7.9 s. What is the car's average acceleration in mph/s?

Anna007 [38]

Answer:

a = 7.6\ mph/s

Explanation:

Motion With Constant Acceleration

It's a type of motion in which the velocity of an object changes uniformly in time.

The equation that describes the change of velocities is:

$v_f=v_o+at$

Where:

a = acceleration

vo = initial speed

vf = final speed

t = time

Solving the equation [for a:

$\displaystyle a=\frac{v_f-v_o}{t}$

The car accelerates from vo=0 to vf=60 mph in t=7.9 s, thus the acceleration is:

$\displaystyle a=\frac{60 \ mph-0}{7.9}$

a = 7.6\ mph/s

7 0

3 years ago

Compare and contrast instantaneous and average speed.

Harlamova29_29 [7]

Answer:

instantaneous velocity is a velocity covered at an instant while average velocity is the change in distance/ the change in time taken

6 0

2 years ago

The tendency for an object at rest to remain at rest

Zarrin [17]

Inertia is the force in play here

7 0

3 years ago

An alternator consists of a coil of area A with N turns that rotates in a uniform field B around a diameter perpendicular to the

svet-max [94.6K]

Answer:

(a): emf = $\rm 2\pi f NBA\sin(2\pi ft).$

(b): Amplitude of alternating voltage = 20.942 Volts.

Explanation:

Given:

Area of the coil = A.
Number of turns of coil = N.
Magnetic field = B
Rotation frequency = f.

(a):

The magnetic flux through the coil is given by

$\phi = \vec B \cdot \vec A=BA\cos\theta$

where,

$\vec A$ = area vector of the coil directed along the normal to the plane of the coil.

$\theta$ = angle between $\vec B$ and $\vec A$ .

Assuming, the direction of magnetic field is along the normal to the plane of the coil initially.

At any time t, the angle which magnetic field makes with the normal to the plane of the coil is $2\pi ft$

Therefore, the magnetic flux linked with the coil at any time t is given by

$\phi(t) = NBA\cos(2\pi ft)$

According to Faraday's law of electromagnetic induction, the emf induced in the coil is given by

$e=-\dfrac{d\phi}{dt}\\=-\dfrac{d(NBA\cos(2\pi ft))}{dt}\\=-NBA(-2\pi f\sin(2\pi ft))\\=2\pi f NBA\sin(2\pi ft).$

(b):

The amplitude of the alternating voltage is the maximum value of the emf and emf is maximum when $\sin(2\pi ft)=1.$

Therefore, the amplitude of the alternating voltage is given by

$e_o = 2\pi ft NBA.$

We have,

$N=100\\A=10^{-2}\ m^2\\B=0.1\ T\\f=2000\ rev/ min = 2000\times \dfrac{1}{60}\ rev/sec=33.33\ rev/sec.$

Putting all these values,

$e_o = 2\pi \times 33.33\times 100\times 0.1\times 10^{-2}=20.942\ Volts.$

7 0

3 years ago