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3 years ago

Define what is energy and work

1 answer:

8 0

The work-energy principle states that an increase in the kinetic energy of a rigid body is caused by an equal amount of positive work done on the body by the resultant force acting on that body. Conversely, a decrease in kinetic energy is caused by an equal amount of negative work done by the resultant force.

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Signment

jeka94

Answer:

v = 5.15 m/s

Explanation:

At constant velocity, the cable tension will equal the car weight of 984(9.81) = 9,653 N

As the cable tension is less than this value, the car must be accelerating downward.

7730 = 984(9.81 - a)

a = 1.95 m/s²

kinematic equations s = ut + ½at² and v = u + at

-5.00 = u(4.00) + ½(-1.95)4.00²

u = 2.65 m/s the car's initial velocity was upward at 2.65 m/s

v = 2.65 + (-1.95)(4.00)

v = -5.15 m/s

3 0

3 years ago

A fan blade, initially at rest, rotates with a constant acceleration of 0.029 rad/s2. What is the time interval required for it

LenKa [72]

Answer:

The time interval is $t = 21.30 \ s$

Explanation:

From the question we are told that

The constant acceleration is $\alpha = 0.029 \ rad / s^2$

The displacement is $\theta = 6.58 \ rad$

According to the second equation of motion we have that

$\theta = w_i* t + \frac{1}{2} * \alpha t^2$

given that the blade started from rest

$w_i$ which is the initial angular velocity is 0

$\theta = 0 + \frac{1}{2} * \alpha t^2$

=> $t = \sqrt{ \frac{2 * \theta }{\alpha } }$

substituting values

=> $t = \sqrt{ \frac{2 * 6.58 }{0.029 } }$

=> $t = 21.30 \ s$

6 0

3 years ago

If you hold a permanent magnet the wrong way in an extremely strong magnetic f eld, its magnetization will be permanently revers

Phoenix [80]

Answer: The domain that is aligned with the applied field will grow, while the domain that is oppositely aligned to the magnetic field will shrink, this is because permanent magnets produces their own magnetic field.

4 0

3 years ago

A block is balanced on top of a frictionless sphere of radius R. When the block is given a slight nudge it starts to slide down

Nataly_w [17]

Answer: $\frac{R}{3}$

Explanation:

Given

Sphere of Radius R

Suppose mass of block is m

At any instant \theta Normal reaction(N) and weight(mg) is acting such that

$mg\sin \theta -N=\frac{mv^2}{R}$ , where v is velocity of block at any angle \theta

When block is just about to leave then N=0

therefore

$mg\sin \theta =\frac{mv^2}{R}$

$v^2=gR\sin \theta$ -------------------1

Also by conserving Energy we get

Potential Energy=kinetic Energy of block

$mgh=\frac{mv^2}{2}$

here h=vertical distance traveled by block

From diagram

$h=R-R\sin \theta$

$h=R(1-\sin \theta )$

$mgR(1-\sin \theta )=\frac{mv^2}{2}$

$2gR(1-\sin \theta )=v^2$ -----------------2

From 1 and 2

$2(1-\sin \theta )=\sin \theta$

$3\sin \theta =2$

$\sin \theta =\frac{2}{3}$

Thus from this value of h is

$h=R(1-\sin \theta )$

$h=R(1-\frac{2}{3})$

$h=\frac{R}{3}$

3 0

4 years ago

A vertical straight wire 35.0 cmcm in length carries a current. You do not know either the magnitude of the current or whether t

12345 [234]

Answer:

$1.714\ \text{A}$

Explanation:

F = Magnetic force = 0.018 N

B = Magnetic field = 0.03 T

L = Length of wire = 35 cm

$\theta$ = Angle between current and magnetic field = $90^{\circ}$

Magnetic force is given by

$F=IBL\sin\theta\\\Rightarrow I=\dfrac{F}{BL\sin\theta}\\\Rightarrow I=\dfrac{0.018}{0.03\times 35\times 10^{-2}\times \sin90^{\circ}}\\\Rightarrow I=1.714\ \text{A}$

The magnitude of the current is $1.714\ \text{A}$ .

8 0

3 years ago

Define what is energy and work​

Define what is energy and work