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
Eddi Din [679]
3 years ago
13

A penny falls from a windowsill which is 25.0 m above the sidewalk. How much time does a passerby on the sidewalk below have to

move out of the way before the penny hits the ground?
Physics
1 answer:
Yanka [14]3 years ago
4 0
You need to know the formula:

25 = 1/2 * g * t^2

t = √(50/g) = 2.258 s, where I use g = 9.8 m/s^2
You might be interested in
A centrifuge rotor (hollow disk) is rotating at 10,000 rpm is shut off and brought to rest by a constant frictional torque of 1.
Y_Kistochka [10]

Answer:

The no of revolutions rotor turn before coming to rest is 1,601.1943 and time taken is equal to 19.21 seconds

Explanation:

here we know that torque = I×α

     α= angular acceleration

     I = moment of inertia of hollow disc = m×k^{2}

  given that m=4.37kg

                    k=0.0710m

           torque=1.2Nm

        w_{o}=10000\times \frac{\pi}{30} rad /s

         \alpha =\frac{torque}{I}

from the above equation we can calculate the angular acceleration of the hollow disc .

  since  w^{2}-w_o^{2} =2\alpha\theta

 from this above equation  \theta=\frac{w^{2}-w_{o}^{2}}{2\alpha }

   no of revolutions = \frac{\theta}{2\pi}  = 1,601.1943.

Now to calculate time we know that time = \frac{2\theta}{w+w_{o}}

   so upon calculating we will be getting t=19.21 seconds

5 0
3 years ago
Which three metal do you think might be present in alnico explain ? ans which one are magnetic​
erma4kov [3.2K]

Answer:

Aluminium, Nickel, Cobalt and Iron plus varying levels of Copper, Titanium and Niobium.

MAGNETIC: Alni, Alcomax, Hycomax, Columax, and Ticonal.

8 0
3 years ago
A thin insulating rod is bent into a semicircular arc of radius a, and a total electric charge Q is distributed uniformly along
storchak [24]

Answer:

v = \frac{kQ}{a}  

Explanation:

We define the linear density of charge as:

\lambda = \frac{Q}{L}

     Where L is the rod's length, in this case the semicircle's length L = πr

The potential created at the center by an differential element of charge is:

dv = \frac{kdq}{r}

          where k is the coulomb's constant

                     r is the distance from dq to center of the circle

Thus.

v = \int_{}^{}\frac{kdq}{a}  

v = \frac{k}{a}\int_{}^{}dq

v = \frac{kQ}{a}     Potential at the center of the semicircle

4 0
3 years ago
Which person is weightless?
ahrayia [7]

Answer: Option (b) is the correct answer.

Explanation:

The force of gravity acting on an object helps in determining the weight of an object. But a place where there will be no gravity or have zero gravitational pull then it means the person will be weightless.

For example, force of gravity on moon is zero which means any object or person on moon will be weightless.

On the other hand, when a child is in the air as she plays on a trampoline then it means gravitational pull form the earth is acting on it. So, it will definitely has some weight.

Similarly, a scuba diver exploring a deep-sea wreck is under the ground where there will be force of gravity. Hence, it will also have some weight.

Thus, we can conclude that an astronaut on the Moon is the person who is weightless.

7 0
3 years ago
You have an initial velocity of -3.0 m/s. You then experience an acceleration of 2.5 m/s2 for 9.0s; what
Tatiana [17]
27.9 idkkkk look it up on photomath
8 0
3 years ago
Other questions:
  • What are some methods humans have used to control flooding and what has been done to worsen the effects of flooding?
    13·1 answer
  • Taylor drives 5 miles in 10 minutes. She stops at a light for 2 minutes. She then travels another 10 miles in 8 minutes. What wa
    14·1 answer
  • What other forces affect the soccer ball after the student's foot stops touching it?
    5·2 answers
  • An electron with a charge of -1.6 × 10-19 coulombs experiences a field of 1.4 × 105 newtons/coulomb. What is the magnitude of th
    12·2 answers
  • To which layer can geologists apply the principle of faunal succession to determine the age of the layer?
    12·2 answers
  • Feeling slightly uncomfortable during exercise
    12·1 answer
  • Seems knows the mass of a basketball what other information is needed to find the balls potential energy
    9·1 answer
  • You are an astronaut on a spacewalk to fix your spacecraft with a hammer. Your lifeline (tether) breaks and your jetpack on your
    14·2 answers
  • A force that opposes motion in moving parts is friction. <br><br> A. true<br> b false
    6·2 answers
  • A car runs along a horizontal path at speed of 20m/s.The driver observes the rain hitting his car at 60 to vertical.If rain is a
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!