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bonufazy [111]
3 years ago
15

Determine whether the following statements are true or false and give an explanation or counter example. a. If the acceleration

of an object remains​ constant, then its velocity is constant. b. If the acceleration of an object moving along a line is always​ 0, then its velocity is constant. c. It is impossible for the instantaneous velocity at all times atb to equal the average velocity over the interval atb. d. A moving object can have negative acceleration and increasing speed.\
Physics
1 answer:
stiks02 [169]3 years ago
8 0

Answer:

A.) False

B.) True

C.) True

D.) False

Explanation:

a. If the acceleration of an object remains​ constant, then its velocity is constant. False because if velocity is constant, acceleration will be equal to zero.

b. If the acceleration of an object moving along a line is always​ 0, then its velocity is constant. Yes. According to definition of acceleration, saying it is the rate of change of velocity. So if velocity is not changing, acceleration = 0

c. It is impossible for the instantaneous velocity at all times at b to equal the average velocity over the interval at b. Yes. Because of constant velocity

d. A moving object can have negative acceleration and increasing speed. False. Because when an object is coming to rest velocity is always reducing.

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Light travels approximately 982,080,000 ft/s, and one year has approximately 32,000,000 seconds. A light year is the distance li
Anastasy [175]

Answer: 3.142656 × 10^16 feet

Explanation: Given that the

Speed = 982,080,000 ft/s, and

Time = 32,000,000 seconds

The formula for speed is:

Speed = distance/ time

Make distance the subject of formula

Since the time is second in one year and speed is ft/s, substitute both into the formula

Distance = speed × time

distance = 982,080,000 × 32,000,000

Distance = 3.142656 × 10^16 feet.

The distance of one light year in feet is 3.142656 × 10^16

8 0
3 years ago
A stuntman with a mass of 80.5 kg swings across a moat from a rope that is 11.5 m. At the bottom of the swing the stuntman's spe
goldenfox [79]

Answer:

  • No
  • 5.49 m/s

Explanation:

The net force required to accelerate the stuntman in a circular arc of radius 11.5 m will be ...

  F = mv²/r . . . . where this m is the mass being accelerated, v is the tangential velocity, and r is the radius.

Here, the net force needs to be ...

  F = (80.5 kg)(8.45 m/s)²/(11.5 m) . . . . . where this m is meters

  ≈ 499.8175 kg·m/s² = 499.8 N

Gravity exerts a force on the stuntman of ...

  F = mg = (80.5 kg)(9.8 m/s²) = 788.9 kg·m/s² = 788.9 N

Then the tension required in the rope/vine is ...

  499.8 N+788.9 N= 1288.7 N

This is more than the capacity of the rope, so we do not expect the stuntman to make it across the moat.

_____

The allowed net force for centripetal acceleration is ...

  1000 N -788.9 N = 211.1 N

Then the allowed velocity is ...

  211.1 = 80.5v²/11.5

  30.16 = v² . . . .  multiply by 11.5/80.5

  5.49 = v . . . . . . take the square root

The maximum speed the stuntman can have is 5.49 m/s.

_____

<em>Comment on crossing the moat</em>

The kinetic energy at the bottom of the swing translates to potential energy at the end of the swing. At the lower speed, the stuntman cannot rise as high, so will traverse a shorter arc. At 8.45 m/s, the moat could be about 16.8 m wide; at 5.49 m/s, it can only be about 11.5 m wide.

5 0
2 years ago
A modern compact fluorescent lamp contains 1.4 mg of mercury (Hg). If each mercury atom in the lamp were to emit a single photon
Reika [66]

Answer:

A. 1.64 J

Explanation:

First of all, we need to find how many moles correspond to 1.4 mg of mercury. We have:

n=\frac{m}{M_m}

where

n is the number of moles

m = 1.4 mg = 0.0014 g is the mass of mercury

Mm = 200.6 g/mol is the molar mass of mercury

Substituting, we find

n=\frac{0.0014 g}{200.6 g/mol}=7.0\cdot 10^{-6} mol

Now we have to find the number of atoms contained in this sample of mercury, which is given by:

N=n N_A

where

n is the number of moles

N_A=6.022\cdot 10^{23} mol^{-1} is the Avogadro number

Substituting,

N=(7.0\cdot 10^{-6} mol)(6.022\cdot 10^{23} mol^{-1})=4.22\cdot 10^{18} atoms

The energy emitted by each atom (the energy of one photon) is

E_1 = \frac{hc}{\lambda}

where

h is the Planck constant

c is the speed of light

\lambda=508 nm=5.08\cdot 10^{-7}nm is the wavelength

Substituting,

E_1 = \frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{5.08\cdot 10^{-7} m}=3.92\cdot 10^{-19} J

And so, the total energy emitted by the sample is

E=nE_1 = (4.22\cdot 10^{18} )(3.92\cdot 10^{-19}J)=1.64 J

4 0
3 years ago
The reckless risk taking found among many adolescents is most likely due to the effects of _______.
ivanzaharov [21]
The reckless risk taking found among many adolescents is most likely due to the effects of        <span>Peer pressure</span>
8 0
3 years ago
Read 2 more answers
Two identical cars, one on the moon and one on the earth, have the same speed and are rounding banked turns that have the same r
Naily [24]

Answer:

The value of the centripetal forces are same.

Explanation:

Given:

The masses of the cars are same. The radii of the banked paths are same. The weight of an object on the moon is about one sixth of its weight on earth.

The expression for centripetal force is given by,

F_{c} = \dfrac{mv^{2}}{r}

where, m is the mass of the object, v is the velocity of the object and r is the radius of the path.

The value of the centripetal force depends on the mass of the object, not on its weight.

As both on moon and earth the velocity of the cars and the radii of the paths are same, so the centripetal forces are the same.

3 0
3 years ago
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