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Shalnov [3]
3 years ago
9

Lara has noticed that all of her friends are very careful about what they eat, and they are all much thinner than she is. She wa

nts to be healthy, but she really wants to fit in with her friends. What is the best step for Lara to take?
A. Talk to a trusted adult to help her evaluate her eating and exercise in a healthy way.
B.Ask her friends how they stay so thin, and use the same strategies.
C. Find new friends who are not as thin so she doesn't feel any pressure.
D.Try out the newest diet she's seen advertised on TV to help her lose the weight she wants to lose.
Physics
2 answers:
nlexa [21]3 years ago
7 0

A. Talk to a trusted adult to help her evaluate her eating and exercise in a healthy way.


HACTEHA [7]3 years ago
5 0

Answer: Option (A) is the correct answer.

Explanation:

If Lara wants to be healthy, and really wants to fit in with her friends then she should talk to a trusted adult to help her evaluate her eating and exercise in a healthy way.

This is because a trusted person will give her beneficial advice as compared to any other person or any advertisement on TV which may promise false results in order to sell their product.

This may also lead to harmful effects on her health. Thus, she should eat and exercise in a healthy way.

You might be interested in
A disk of radius R = 11 cm is pulled along a frictionless surface with a force of F = 16 N by a string wrapped around the edge.A
kenny6666 [7]

Answer: 1.76 Nm

Explanation:

If the force pulls horizontally, this means that the force is tangent to the disk at any point of the string unwinding process, so the distance d is irrelevant.

In this case, the torque is directly given by the product of the force times the distance perpendicular to the center of the disk, which is just the radius, as follows:

τ = F * r = 16 N. (0.11) m = 1.76 Nm

7 0
3 years ago
A 4.00-g bullet, traveling horizontally with a velocity of magnitude 400 m/s, is fired into a wooden block with mass 0.650 kg ,
Maru [420]

Answer:

a) Coefficient of kinetic friction between block and surface = 0.12

b) Decrease in kinetic energy of the bullet = 247.8 J

c) Kinetic energy of the block at the instant after the bullet passes through it = 0.541 J

Explanation:

Given,

Mass of bullet = 4.00 g = 0.004 kg

Initial velocity of the bullet = 400 m/s

Mass of wooden block = 0.65 kg

Initial velocity of the wooden block = 0 m/s (since it was initially at rest)

Final velocity of the bullet = 190 m/s

Distance slid through by the block after the collision = d = 72.0 cm = 0.72 m

Let the velocity of the wooden block after collision be v

According to the law of conservation of momentum,

Momentum before collision = Momentum after collision

Momentum before collision = (Momentum of bullet before collision) + (Momentum of wooden block before collision)

Momentum of bullet before collision = (0.004×400) = 1.6 kgm/s

Momentum of wooden block before collision = (0.65)(0) = 0 kgm/s

Momentum after collision = (Momentum of bullet after collision) + (Momentum of wooden block after collision)

Momentum of bullet after collision = (0.004×190) = 0.76 kgm/s

Momentum of wooden block after collision = (0.65)(v) = (0.65v) kgm/s

Momentum balance gives

1.6 + 0 = 0.76 + 0.65v

0.65v = 1.6 - 0.76 = 0.84

v = (0.84/0.65)

v = 1.29 m/s

The velocity of the wooden block after collision = 1.29 m/s

To obtain the coefficient of kinetic friction between block and surface, we will apply the work-energy theorem.

The work-energy theorem states that the work done in moving the block from one point to another is equal to the change in kinetic energy of the block between these two points.

The points to consider are the point when the block starts moving (immediately after collision) and when it stops as a result of frictional force.

Mathematically,

W = ΔK.E

W = workdone by the frictional force in stopping the wooden block (since there is no other horizontal force acting on the block)

W = -F.d (minus sign because the frictional force opposes motion)

d = Distance slid through by the block after the collision = 0.72 m

F = Frictional force = μN

where N = normal reaction of the surface on the wooden block and it is equal to the weight of the block.

N = W = mg

F = μmg

W = - μmg × d = (-μ)(0.65)(9.8) × 0.72 = (-4.59μ) J

ΔK.E = (final kinetic energy of the block) - (initial kinetic energy of the block)

Final kinetic energy of the block = 0 J (since the block comes to a rest)

(Initial kinetic energy of the block) = (1/2)(0.65)(1.29²) = 0.541 J

ΔK.E = 0 - 0.541 = - 0.541 J

W = ΔK.E

-4.59μ = -0.541

μ = (0.541/4.59)

μ = 0.12

b) The decrease in kinetic energy of the bullet

(Decrease in kinetic energy of the bullet) = (Kinetic energy of the bullet before collision) - (Kinetic energy of the bullet after collision)

Kinetic energy of the bullet before collision = (1/2)(0.004)(400²) = 320 J

Kinetic energy of the bullet after collision = (1/2)(0.004)(190²) = 72.2 J

Decrease in kinetic energy of the bullet = 320 - 72.2 = 247.8 J

c) Kinetic energy of the block at the instant after the bullet passes through it = (1/2)(0.65)(1.29²) = 0.541 J

Hope this Helps!!!

4 0
3 years ago
What is a half-life?
Serggg [28]

Answer:

option D is correct

Explanation:

5 0
3 years ago
Read 2 more answers
By what factor is the intensity of sound at a rock concert louder than that of a whisper when the two intensity levels are 120 d
Kipish [7]

Answer:

The intensity of sound at a rock concert is louder than that of a whisper by a factor of 1 x 10¹⁰

Explanation:

Given;

rock concert sound intensity level, β₁ = 120 dB

whisper sound intensity level, β₂ = 20 dB

The sound intensity level is given as;

\beta = 10Log(\frac{I}{I_o} )\\\\

where;

I₀ is the threshold sound intensity of hearing = 10⁻¹² W/m²

I is the sound intensity

Intensity of sound at rock concert ;

120 =  10Log(\frac{I}{10^{-12}} )\\\\12 =  Log(\frac{I}{10^{-12}} )\\\\10^{12} = \frac{I}{10^{-12}}\\\\I = 10^{12}  * 10^{-12}\\\\I = 10^0\\\\I = 1 \ W/m^2

The intensity of sound of a whisper;

20 =  10Log(\frac{I}{10^{-12}} )\\\\2 =  Log(\frac{I}{10^{-12}} )\\\\10^{2} = \frac{I}{10^{-12}}\\\\I = 10^{2}  * 10^{-12}\\\\I = 10^{-10} \ W/m^2\\\\

Determine the factor by which the intensity of sound at a rock concert louder than that of a whisper

\frac{I_{Concert}}{I_{whisper}} = \frac{1}{10^{-10}} \\\\\frac{I_{Concert}}{I_{whisper}} = 1 * 10^{10}\\\\I_{Concert} = 1 * 10^{10}*I_{whisper}

Therefore, the intensity of sound at a rock concert is louder than that of a whisper by a factor of 1 x 10¹⁰

3 0
3 years ago
If the density of a diamond is 3.5 /cm^ 3 what would be the mass of a diamond whose volume is 0.5 cm ^ 3 ?
Elan Coil [88]

Answer:

1.75g

Explanation:

Given parameters:

Density  = 3.5g/cm³

Volume  = 0.5cm³  

Unknown:

Mass of the diamond  = ?

Solution:

Density is the mass per unit volume of a substance

  Density  = \frac{mass}{volume}  

So;

  Mass  = 3.5 x 0.5  = 1.75g

7 0
3 years ago
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