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irga5000 [103]
4 years ago
14

Paul lifts a sack weighing 245 newtons vertically from the ground and places it on a platform at a height of 0.7 meters. If he t

akes 10 seconds to do this task, what power has he expended during this time? A. 10 watts B. 17.15 watts C. 23.6 watts D. 29.8 watts
Physics
1 answer:
d1i1m1o1n [39]4 years ago
6 0

Answer:

B. 17.15 watts

Explanation:

Given that

Time = 10 seconds

height = distance = 0.7 meters

weight of sack = mg = F = 245 newtons

Power = work done/ time taken

Where work done = force × distance

Substituting the given parameters into the formula

Work done = 245 newton × 0.7 meters

Work done = 171.5 J

Recall,

Power = work done/time

Power = 171.5 J ÷ 10

Power = 17.15 watts

Hence the power expended is B. 17.15 watts

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A person, with his ear to the ground, sees a huge stone strike the concrete pavement. A moment later two sounds are heard from t
s344n2d4d5 [400]

Answer:

309 m

Explanation:

time apart = 0.8 s

speed of sound in air = 343 m/s

speed of sound in concrete = 3000 m/s

lets assume it time it takes to travel trough concrete = T

the time it takes to travel through air = T + 0.8 since they are 0.8 s apart

the distance traveled by both waves is the same, so we can equate the distance for both waves

distance  = speed x time

  • for concrete, distance = 3000 x T
  • for air, distance = 343 x (T + 0.8)

now equating the two distance together we have

3000 x T  = 343 x (T + 0.8)

3000T = 343T + 274.4

3000T - 343T = 274.4

T = 0.103 s

recall that distance = 3000 x T = 3000 x 0.103 = 309 m

5 0
3 years ago
What would happen if there were no enzymes in the human body?
MakcuM [25]

Answer:

Explanation:wwwwwwwwwwwwwwwwwwwwww

6 0
4 years ago
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A .5kg bird is perched on its nest so that it has 50J of potential energy. how far is it off the of the ground?
pshichka [43]

It is 10.20 m from the ground.

<u>Explanation:</u>

<u>Given:</u>

m = 0.5 kg

PE = 50 J

We know that the Potential energy is calculated by the formula:

P. E = m \times g \times h

where m is the is mass in kg;  g  is acceleration due to gravity which is 9.8 m/s  and  h  is height in meters.

PE is the Potential Energy.

Potential Energy is the amount of energy stored when an object is stationary.

Here, if we substitute the values in the formula, we get

P. E = m \times g \times h

50 = 0.5 × 9.8 × h

50 = 4.9 × h

h = \frac {50} {4.9}

h = 10.20 m

3 0
3 years ago
Which of the following is a type of object that might contain billions of stars?
Alexxx [7]
A galaxy because that is the largest group and contains many things.

6 0
4 years ago
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A 50.0-kg block is being pulled up a 13.0° slope by a force of 250 N which is parallel to the slope, but the block does not slid
Elan Coil [88]

<span>Weight of block, Wb = mass*gravity = 50*9.8 = 490 N</span>

Since block is being pulled up by a 13-degree slope

Therefore, Force which is acting parallel to the slop:

<span> F p =490 Sin </span>13^{0}= 110.2N

Force which is acting perpendicular to the slope:

<span> Fv =490 Cos</span>13^{0} = 477.4 N

Net force can be given as follows:

<span>F n = (250 - 110.2 - 0.2*</span>477.4) N

<span>Fn=44.3N</span>

Now acceleration is given by the ratio of force to mass

<span>a = Fn/m</span>

<span>=44.3/50 = 0.89 ms^<span>-2</span></span>

8 0
3 years ago
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