1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
8090 [49]
3 years ago
14

A person struggles very hard to lift a large boulder. He puts in so much effort, he starts to sweat, his heart rate increases, a

nd he gets really tired. All of his effort is for nothing, the boulder does not move at all. In this situation, has work been done? Explain!
*Use the scientific definition of "work" to answer this question.
Physics
1 answer:
Lesechka [4]3 years ago
5 0
No, he did not perform any work. Work is when you’re using energy which results in a force. Even though he was tired and sweaty, he did not move the boulder. So therefore he did not perform any work.
You might be interested in
A horizontal beam of light of intensity 25 W/m2 is sent through two polarizing sheets. The polarizing direction of the first mak
Zina [86]

Answer:

option (B)

Explanation:

Intensity of unpolarised light, I = 25 W/m^2

When it passes from first polarisr, the intensity of light becomes

I'=\frac{I_{0}}{2}=\frac{25}{2}=12.5 W/m^{2}

Let the intensity of light as it passes from second polariser is I''.

According to the law of Malus

I'' = I' Cos^{2}\theta

Where, θ be the angle between the axis first polariser and the second polariser.

I'' = 12.5\times Cos^{2}15

I'' = 11.66 W/m^2

I'' = 11.7 W/m^2

7 0
3 years ago
P2O5 is a covalent compound used to purify sugar. What is the name of this compound?
AfilCa [17]

Answer:

B) Diphosphorus pentoxide

Explanation:

8 0
3 years ago
Read 2 more answers
PLEASE HELPPPP!!!<br> Density is the amount of mass per unit volume.<br><br><br> True or False
Alexxandr [17]

Answer:

true :D

Explanation:

4 0
3 years ago
a new planet is discovered that has twice the earth’s mass and twice the earth’s radius. on the surface of this new planet, a pe
Irina18 [472]

Answer: 250n

Explanation:

The formula for gravitational force is: F = (gMm)/r^2

There are two factors at play here:

1) The mass of the planet 'M'

2) The radius 'r'

We can ignore the small M and the g, they are constants that do not alter the outcome of this question.

You can see that both M and r are double that of earth. So lets say earth has M=1 and r=1. Then, new planet would have M=2 and r=2. Let's sub these two sets into the equation:

Earth. F =  M/r^2 = 1/1

New planet. F = M/r^2 = 2/4 = 1/2

So you can see that the force on the new planet is half of that felt on Earth.

The question tells us that the force on earth is 500n for this person, so then on the new planet it would be half! So, 250n!

8 0
2 years ago
Joe is attempting to ramp his bicycle over a row of burning tires. If the ramp has a launch angle of 20 degrees, and Joe can ped
Luden [163]
Answer is 6 tires.

This is a projectile question.

First make sure units are consistent - express speed in m/s.

20 km/h = 20000m / 3600 s = 5.56 m/s

Assume the takeoff point of the ramp is at ground level (height, h, = 0m). We need to determine how long Joe is in the air, and use that time to calculate the horizontal distance he traveled.

Joe is traveling 5.56 m/s on a ramp angled at 20 degrees. There are vertical and horizontal components to his speed:

Vertical speed = 5.56sin20 = 1.90 m/s
Horizontal speed = 5.56cos20 = 5.22 m/s

An easy way to proceed is to calculate the time it takes for Joe’s vertical speed to reach 0m/s - this represents the time when Joe is at his maximum height and is therefore halfway through the trip. Double whatever time this is to find the total time of the trip. Remember he is decelerating due to gravity:

Time to peak:
a = Δv / Δt
-9.8 = -1.9 / Δt
Δt = 0.19s

Total trip time:
0.19 x 2 = 0.38s

Now that we have the total tome Joe is in the air, we can find the horizontal distance he traveled:

v = d / t
5.22 = d / 0.38
d = 1.98m

Now divide this total distance by the length of an individual tire to find the number of tires he will clear:

1.98 / 0.3 = 6.6 tires

Therefore he can jump 6 tires safely (he will land in the middle of the 7th tire).

Lots of steps I know but just try to think of the situation and keep track of the vertical and horizontal things!
4 0
3 years ago
Other questions:
  • A student constructed a series circuit consisting of a 12.0-volt battery, a 10.0-ohm lamp, and a
    8·1 answer
  • Which of these is an example of a chemical reaction that occurs at a very slow rate?
    12·2 answers
  • A force of 50 newtons causes a sled to accelerate at a rate of 5 meters per second. What is the mass of the sled.
    6·2 answers
  • The 26-kg sphere c is released from rest when θ = 0∘ and the tension in the spring is f = 100 n
    15·1 answer
  • How are mm hg torr psi atm and pa related to each other mathematically?
    14·1 answer
  • What is the smallest unit that makes up matter
    14·2 answers
  • Arrange the skin layers according to the order in which a physician would cut them off during surgery, starting with the first a
    13·1 answer
  • To subtract displacements, a ____________ needs to be set
    8·1 answer
  • The acceleration of an object would increase if there was an increase in the
    15·1 answer
  • When light passes the
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!