A man weighs himself twice in an elevator. When the elevator is at rest, he weighs 824 N; when the elevator starts moving upward, he weighs 932 N. Most nearly how fast is the elevator accelerating, assuming constant acceleration?

a. 0.64 m/s
b. 1.1 m/s^2
c. 1.3 m/s
d. 9.8 m/s^2

Answer:

[tex]\frac{dh}{dt}=-0.4125 m/s[/tex]

Explanation:

The very first thing we can do here is to draw a sketch of the situation the problem is presenting. (See attached picture)

As you may see in the picture, we can suppose the spotlight is directly located on the ground so the light of the spotlight together with the person and the wall make two similar triangles.

In this case we need to think about the dimensions of the triangle that will change over time. We will call them:

x= distance between the spotlight and the man.

h= height of the shadow.

So we can build a relation between the height and the length of each triangle:

[tex]\frac{h}{12}=\frac{2}{x}[/tex]

the distance between the spotlight and the wall is constant, so I can directly write the 12 in my equation and the height of the man is constant as well, so I can write the 2 directly into the equation.

Next, we can solve the equation for h (since we are interested in figuring out how fast the height of the shadow is decreasing) so we get:

[tex]h=\frac{24}{x}[/tex]

So next, we need to take the derivative of the equation, since the derivative of a position function will give us the velocity at which that position is changing.

First we rewrite the equation like this:

[tex]h=24x^{-1}[/tex]

and take the derivative:

[tex]dh=-24x^{-2}dx[/tex]

we can rewrite the derivative like this:

[tex]\frac{dh}{dt}=-\frac{24}{x^{2}} \frac{dx}{dt}[/tex]

where:

dh/dt is the velocity at which the height of the shadow is decreasing (that's why our equation has a negative sign in front of it).

dx/dt is the velocity at which the value of x is increasing. In other words, how fast the man is moving away from the spotlight.

So we can go ahead and substitute:

we wish to find the velocity at which the shadow's height is decreasing when the distance between the man and the building is 4m, so in this case, x=12-4=8m

[tex]\frac{dh}{dt}=-\frac{24}{8^{2}}(1.1 m/s)[/tex]

so we get:

[tex]\frac{dh}{dt}=-0.4125 m/s[/tex]

Answer:

F = 133.33[N]

Explanation:

This problem can be solved by the principle of momentum conservation, which tells us that momentum is preserved before and after the bounce of the ball on the wall.

In such a way that the movement towards the wall we will take it with a positive sign, and the force of the rebound to the left as negative. The movement to the left will be taken as a negative sign.

[tex]m_{1}*v_{1}-F*t=-m_{1}*v_{2}[/tex]

where:

m₁ = mass of the object = 1.5 [kg]

v₁ = velocity of the ball before hitting the wall = 2.5 [m/s]

F = average force [N]

t = time contact = 0.045 [s]

v₂ = velocity of the ball after hitting the wall = 1.5 [m/s]

Now replacing:

[tex](1.5*2.5)-F*0.045=-(1.5*1.5)\\3.75+2.25=F*0.045\\F=6/0.045\\F=133.33[N][/tex]

Answer:

first where is figure...

silver the is best conducter of electricity.

Answer:

5m

Explanation:

[tex]4^{2}+3^{2}=5^{2}\\5^{2}=25[/tex]

Use the Pythagorean theorem to calculate the long edge of the triangle, which would be his displacement.

Answer:

E = 105.84  J

Explanation:

Given that,

Mass of cat, m = 3.6 kg

It is laying 3 meters above the ground.

We need to find the cat's potential energy. The formula for the potential energy of an object is given by :

E = mgh

Substituting all the values,

E = 3.6 kg × 9.8 m/s²×3 m

E = 105.84  J

So, the cat's potential energy is 105.84  J.

The force acts on this bullet : 4.8456 N

Given

m=0.09 kg

Δt=0.025 s

vo=0(from rest)

vt=1.346 m/s

Required

Force

Solution

Impulse is a change in momentum

I=ΔP

F.Δt=m(vt-vo)

Input the value

F x 0.025 = 0.09(1.346-0)

F=4.8456 N

Answer:

[tex]\huge\boxed{\sf P.E. = 39.2\ Joules}[/tex]

Explanation:

Given Data:

Mass = m = 4 kg

Acceleration due to gravity = g = 9.8 m/s²

Height = h = 1 m

Required:

Potential Energy = P.E. = ?

Formula:

P.E. = mgh

Solution:

P.E. = (4)(9.8)(1)

P.E. = 39.2 Joules

[tex]\rule[225]{225}{2}[/tex]

Hope this helped!

Answer:

Kinetic energy is energy of motion

Explanation:

Of potential energy which is energy that is stored

Answer:

1)1*20=20

2)-30/3=- -10

3)velocity of the object 1=v1=4*V2

4) kg m/ s

5) momentum of the system= 12 kg m/ s

sowwie :( i need points

Explanation:

Answer:

Explanation:

The force of gravity depends directly upon the masses of the two objects, and inversely on the square of the distance between them. This means that the force of gravity increases with mass, but decreases with increasing distance between objects

so a option is correct

Answer: tennis ball

Explanation:

Answer:

i think it should be 18

Explanation:

Answer:

100kgms⁻¹

Explanation:

Given parameters:

Mass of the sled  = 20kg

Velocity of the sled  = 5m/s

Unknown:

Momentum of the sled = ?

Solution:

The momentum of a body is the quantity of motion such a body possesses. Due to this;

    Momentum  = mass x velocity

Now insert the parameters and solve;

      Momentum  = 20 x 5  = 100kgms⁻¹

Answer:

F = 318.88[N]

Explanation:

This problem can be solved by the principle of momentum conservation, which tells us that momentum is preserved before and after kicking the ball.

In this way, we can construct the following equation.

[tex]F*t=m*v[/tex]

where:

F = force [N]

t = time = 0.08 [s]

m = mass = 0.41 [kg]

v = velocity [m/s]

[tex]F*0.045=0.41*35\\F=318.88[N][/tex]

Answer:

68.88 m/s

Explanation:

downstream speed = 8+1.9=9.9 m/s

upstream speed = 8-1.9= 6.1 m/s

Therefore, total time taken would be 260/9.9+260/6.1 = 26.26+42.62 =

68.88 m/s

momentum (m)=40

velocity (v)=2

now,

momentum (m)=m×v

40=m×2

m=40÷2

m=20kg

Answer:

3 hrs

Explanation:

the distance covered by victor= 210 km

speed= 70 km/hrs

so, 70×3= 210

so the answer is 3 hrs

BTW im a small kid so don't just right away say the explanation sucks and the subject physics is not yet started in my grade.

edit: don't give me brainless answer plz.

Complete question is;

What is the electrical potential at the surface of gold nucleus? The radius of a gold atom is 6.6 × 10​^(-5) m and atomic number z = 79.

Answer:

172.36 × 10^(-5) V

Explanation:

We are given;

Radius; r = 6.6 × 10^(-5) m

Atomic number; Z = 79

Formula for Electric potential here is;

V = kZe/r

Where;

e is charge on proton = 1.6 × 10^(-19) C

k has a constant value of 9 × 10^(9) N⋅m²/C²,

​Thus;

V = (79 × 1.6 × 10^(-19) × 9 × 10^(9))/(6.6 × 10^(-5))

V = 172.36 × 10^(-5) V

Answer:

The building is 176.4 meters high.

Explanation:

We use the formula for kinematics of an accelerated object (in this case acceleration of gravity):

Distance travelled = 1/2 g  t^2

Distance travelled = 1/2 9.8  (6)^2 = 176.4 meters

Answer:

C

Explanation:

The thermal energy from her hand will go up into the smoothie.

Answer:

C bois

Explanation:

Answer:

It's the number of protons in the nucleus of the atom

Answer:

8000Ns

Explanation:

Given parameters:

Mass of the truck  = 1000kg

Initial velocity  = 9m/s

Final velocity  = 17m/s

Unknown:

Impulse  = ?

Solution:

The impulse experienced by the truck is the the change in momentum of the body.

  Impulse  = Ft

        Momentum  = m(v  - u)

        Ft  = m( v - u )

 F is the force

 t is the time

 m is the mass

  v is the final velocity

 u is the initial velocity

     Impulse  = 1000(17 - 9) = 8000Ns

Answer:

Answer:

1885.2 ohms

Explanation:

Step one:

given data

L=5H

f=60Hz

Required

The inductive reactance of the inductor

Step two:

Applying the expression

XL= 2πfL

substitute

XL=2*3.142*60*5

XL=1885.2 ohms

Answer:

true

Explanation:

I believe the answer i chose because the earths atmosphere is mostly made up of different things that causes the earth to interact with human life and also interacts with what's in the atmosphere like energy oxygen carbon dioxide and all the stuff like that i hope its right.