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3 years ago

1. An electric iron has a rating of 750W, 220V. Calculate:

1 answer:

6 0

The equation for electrical power isP=VIwhere V is the voltage and I is the current. This can be rearranged to solve for I in 6(a). 6(b) can be solved with Ohm's LawV=IRor if you'd like, from power, after substituting Ohm's law in for IP=V2R For 7, realize that because they are in parallel, their voltages are the same. We can find the resistance of each lamp fromP=V2RThen the equivalent resistance as1R∗=1R1+1R2Then the total power asPt=V2R∗However, this will reveal that (with a bit of algebra)Pt=P1+P2 For 8, again the resistance can be found asP=V2RThe energy usage is simplyE=P⋅t

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A ball with mass of 0.050 kg is dropped from a height of h1 = 1 .5 m. It collides with the floor, then bounces up to a height of

Iteru [2.4K]

Answer:

Explanation:

Impulse of reaction force of floor = change in momentum

Velocity of impact = √ 2gh₁

= √ 2 x 9.8 x 1.5 = 5.4 m /s.

velocity of rebound = √2gh₂

= √ 2x 9.8 x 1

= 4.427 m / s.

Initial momentum = .050 x 5.4 = .27 kg m/s

Final momentum = .05 x 4.427 = .22 kg.m/s

change in momentum = .27 - .22 = .05 kg m/s

Impulse = .05 kg m /s

Impulse = force x time

force = impulse / time

.05 / .015 = 3.33 N.

kinetic energy = 1/2 m v²

Initial kinetic energy = 1/2 x .05 x 5.4²

= 0.729 J

Final Kinetic Energy =1/2 x .05 x 4.427²

= 0.489 J

Change in Kinetic energy =0 .24 J

Lost kinetic energy is due to conversion of energy into sound light etc.

4 0

3 years ago

A light beam has speed c in vacuum and speed v in a certain plastic. The index of refraction n of this plastic is

Mnenie [13.5K]

Answer:

$n = \frac{c}{v}$

Explanation:

Refractive Index: It is a measure to find how fast the light travels through a medium. It is ration of the speed of light in vacuum to speed of light in the medium. Speed of light is not constant and varies depending on the density of the medium.

In vacuum the speed of light is 300000 km/s and is denoted by c. When the light beam enters any medium the speed will decrease. Here it is given that the speed in plastic is v. Thus the refractive index(n) is given as:

$n = \frac{c}{v}$

It is a dimensionless no.

3 0

3 years ago

When can a high speed velocity cause damage?'

sweet-ann [11.9K]

Answer:

50 Mph.

Explanation:

According to the National Severe Storms Laboratory, winds can really begin to cause damage when they reach 50 mph. But here’s what happens before and after they reach that threshold, according to the Beaufort Wind Scale (showing estimated wind speeds): - at 19 to 24 mph, smaller trees begin to sway.

7 0

3 years ago

Which of the following can break solid rock

sergeinik [125]

I would think the answer would be c

7 0

3 years ago

Read 2 more answers

Which statement explains whether or not a person should use an experiment of a ball rolling down a hill as evidence that the for

Ksenya-84 [330]

The ball raised up the hill is given gravitational potential energy, which

causes it to roll spontaneously down the hill.

The statement that explains whether the ball rolling down the hill

experiment should be used is; The experiment shows the ball falls toward

the bottom of the hill, so it provides direct evidence that gravity pulls an

object downward. They should use it.

Reason:

The equation for the velocity of a ball falling down a hill is $v = \sqrt{\dfrac{10}{7} \cdot g \cdot h}$

Therefore, by increasing the height from which the ball rolls down the hill,

the velocity of the ball increases, which indicates that the ball is

accelerating, and therefore, being acted on by a force, the force of gravity.

Therefore;

Given that the ball falls or moves with increasing speed towards

the bottom of the hill, which shows that the motion is due to Earth's pull

known as the gravitational force, the experiment should be used.

Learn more here:

brainly.com/question/3175380

8 0

2 years ago