Electric field lines indicate?

In order to determine the coefficients of friction between rubber and various surfaces, a student uses a rubber eraser and an in

Strike441 [17]

Answer:

μs = 0.75

μk = 0.58

Explanation:

From a force diagram:

$m*g*sin \theta - Ff=m*a$ (1)

$N-m*g*cos \theta = 0$ (2)

When it starts slipping, friction force is the maximum and acceleration is 0. Replacing these conditions on (1):

$m*g*sin \theta - \mu*m*g*cos \theta=0$ Solving for μs:

$\mu=tan \theta$

μs = tan 36.7° = 0.75

When it moves at constant speed, friction force is kinetic friction and acceleration is 0. With these conditions the coefficient is:

μk = tan 30.1° = 0.58

8 0

4 years ago

In Europe the standard voltage in homes is 220 V instead of the 120 V used in the United States. Therefore "100-W" European bulb

Maslowich

Explanation:

In Europe the standard voltage in homes is 220 V instead of the 120 V used in the United States.

100-W European bulb would be intended for use with a 220-V potential difference.

(a) If V = 220 V and P = 100 W

Power :

$P=\dfrac{V^2}{R}\\\\R=\dfrac{V^2}{P}\\\\R=\dfrac{(220)^2}{100}\\\\R=484\ \Omega$

If you bring a "100-W" European bulb home to the untied States, what should be its US power rating. So,

$P=\dfrac{V^2}{R}\\\\P=\dfrac{(120)^2}{484}\\\\P=29.75\ W$

or

P = 29.8 watts

(b) Let I is the current will the 100-W European bulb draw in normal use in the United States. So,

$I=\dfrac{V}{R}\\\\I=\dfrac{120}{484}\\\\I=0.248\ A$

Hence, this is the required solution.

3 0

3 years ago

Read 2 more answers

In a Broadway performance, an 77.0-kg actor swings from a R = 3.65-m-long cable that is horizontal when he starts. At the bottom

krek1111 [17]

Answer: h =1.22 m

Explanation:

from the question we were given the following

mass of performer ( M1 ) = 77 kg

length of cable ( R ) = 3.65 m

mass of costar ( M2 ) = 55 kg

maximum height (h) = ?

acceleration due to gravity (g) = 9.8 m/s^2 (constant value)

We first have to find the velocity of the performer. From the work energy theorem work done = change in kinetic energy

work done = 1/2 x mass x ( (final velocity)^2 - (initial velocity)^2 )

initial velocity is zero in this case because the performer was at rest before swinging, therefore

work done = 1/2 x 77 x ( v^2 - 0)

work done = 38.5 x ( v^2 ) ......equation 1

work done is also equal to m x g x distance ( the distance in this case is the length of the rope), hence equating the two equations we have

m x g x R = 38.5 x ( v^2 )

77 x 9.8 x 3.65 = 38.5 x ( v^2 )

2754.29 = 38.5 x ( v^2 )

( v^2 ) = 71.54

v = 8.4 m/s ( velocity of the performer)

After swinging, the performer picks up his costar and they move together, therefore we can apply the conservation of momentum formula which is

initial momentum of performer (P1) + initial momentum of costar (P2) = final momentum of costar and performer after pick up (Pf)

momentum = mass x velocity therefore the equation above now becomes

(77 x 8.4) + (55 x 0) = (77 +55) x Vf

take note the the initial velocity of the costar is 0 before pick up because he is at rest

651.3 = 132 x Vf

Vf = 4.9 m/s

the performer and his costar is 4.9 m/s after pickup

to finally get their height we can use the energy conservation equation for from after pickup to their maximum height. Take note that their velocity at maximum height is 0

initial Kinetic energy + Initial potential energy = Final potential energy + Final Kinetic energy

where

kinetic energy = 1/2 x m x v^2

potential energy = m x g x h

after pickup they both will have kinetic energy and no potential energy, while at maximum height they will have potential energy and no kinetic energy. Therefore the equation now becomes

initial kinetic energy = final potential energy

(1/2 x (55 + 77) x 4.9^2) + 0 = ( (55 + 77) x 9.8 x h) + 0

1584.7 = 1293 x h

h =1.22 m

3 0

4 years ago

Why construction is present near the bulb

vova2212 [387]

Answer:

The constriction causes the mercury column to break under tension, leaving a vacuum between the bottom of the column and that in the bulb, and the top of the column stays still at the position reached in the body - a "peak hold" system.

7 0

4 years ago

The kangaroo stops at a lake for a drink of water, then starts hopping again to the south. After 5 seconds, the kangaroo is goin

kiruha [24]

Answer:

<u>A kangaroo hops 60 m to the east in 5 s. What is the kangaroo's average velocity? ... The kangaroo stops at a lake for a drink of water and then starts hopping again to the south. Each second, the kangaroo's velocity increases 2.5 m/s.</u>

6 0

3 years ago