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HACTEHA [7]
2 years ago
5

Consider a person standing in an elevator that is moving at constant speed upward. The person, of mass m, has two forces acting

upon him, the downward force m g due to gravity, and the upward supporting force n exerted by the floor of the elevator. In this case, which of these two forces has the smaller magnitude?

Physics
2 answers:
Leya [2.2K]2 years ago
8 0

Answer:

The force of gravity

Explanation:

Remember that when sometthing is moving there is always several forces acting on the object, in this case, the gravity is pulling the mass of the person standing downward and the floor of the elevator ispulling upward, the direction of the movement will dictate which force is greater than the other, as the person is moving upward that is the greater force, the force of gravity is the smaller magnitude.

larisa [96]2 years ago
4 0

Answer:

The weight of the person has a smaller magnitude.

Explanation:

For an observer in inertial frame of reference for the person in the elevator Newton's Second Law can be written as

Normal reaction acts upwards

Weight acts downwards

\sum F_{v}=ma_{v}\\\\N-mg=m\times a_{v}\\\\m\times a_{v}> 0\\\\\therefore N-mg> 0\\\\\therefore N> mg

Here

N is the normal reaction force

mg is the weight of the person

g is acceleration due to gravity

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A radioactive substance decays exponentially. A scientist begins with 200 milligrams of a radioactive substance. After 17 hours,
lianna [129]

75.17 mg of the radioactive substance will remain after 24 hours.

Answer:

Explanation:

Any radioactive substance will obey the exponential decay behavior. So according to this behavior, any radioactive substance will be decaying in terms of exponential form of disintegration constant and Time.

Disintegration constant is the rate of decay of radioactive elements. It can be measured using the half life time of the radioactive element .While half life time is the time taken by any radioactive element to decay half of its concentration. Like in this case, at first the scientist took 200 mg then after 17 hours, it got reduced to 100 g. So the half life time of this element is 17 hours.

Then Disintegration constant = 0.6932/Half Life time

Disintegration constant = 0.6932/17=0.041

Then as per the law of disintegration constant:

N = N_{0}e^{-xt}

Here N is the amount of radioactive element remaining at time t and N_{0} is the initial amount of sample, x is the disintegration constant.

So here, N_{0} = 200 mg, x = 0.041 and t = 24 hrs.

N = 200 ×e^{-24*0.041} =75.17 mg.

So 75.17 mg of the radioactive substance will remain after 24 hours.

3 0
2 years ago
Calculate the flux of the vector field F⃗ =−6i⃗ +5x2j⃗ −5k⃗ , through the square of side 8 in the plane y=1, centered on the y-a
Tasya [4]

Answer:

The flux is 682.6 Wb.

Explanation:

Given that,

Vector field F=-6i+5x^2j-5k

We need to calculate the flux

Using formula of flux

\phi=\int_{-4}^{4}\int_{-4}^{4}(F\cdot j\ dxdz)

Put the value into the formula

\phi=\int_{-4}^{4}\int_{-4}^{4}(-6i+5x^2j-5k)1\ dxdz

\phi=\int_{-4}^{4}\int_{-4}^{4}(5x^2)dxdz

\phi=2(\dfrac{x^3}{3})_{-4}^{4}\times(z)_{-4}^{4}

\phi=682.6\ Wb

Hence, The flux is 682.6 Wb.

7 0
2 years ago
5. A 1-kg car and a 2-kg car are both released from the top of the same hill and roll down a frictionless track. At the bottom o
grigory [225]

The cars will have equal speeds and the 2 kg car will have greater kinetic energy.

7 0
2 years ago
: The truck is to be towed using two ropes. Determine the magnitudes of forces FA and FB acting on each rope in order to develop
Sholpan [36]

Answer:

Fa=774 N

Fb=346 N

Explanation:

We will solve this problem by equating forces on each axis.

  1. On x-axis let forces in positive x-direction be positive and forces in negative x-direction be negative
  2. On y-axis let forces in positive y-direction be positive and forces in negative y-direction be negative

While towing we know that car is mot moving in y-direction so net force in y-axis must be zero

⇒∑Fy=0

⇒Fa*sin(50)-Fb*sin(20)=0

⇒Fa*sin(50)=Fb*sin(20)

⇒Fa=2.24Fb

Given that resultant force on car is 950N in positive x-direction

⇒∑Fx=950  

⇒Fa*cos(20)+Fb*cos(50)=950

⇒2.24*Fb*cos(20)+Fb(50)=950

⇒Fb*(2.24*cos(20)+cos(50))=950

⇒Fb=\frac{950}{2.24*cos(20)+cos(50)}

⇒Fb=\frac{950}{2.24*0.94+0.64}

⇒ Fb=\frac{950}{2.75}=345.5

⇒Fa=2.24*Fb

      =2.24*345.5

      =773.93

Therefore approximately, Fa=774 N and Fb=346 N

5 0
2 years ago
A punted football is observed to have velocity components vhorizontal = 15 m/s to the right and vvertical = 1.25 m/s directed do
enot [183]

Answer:

v₀ₓ = 15 m / s,  v_{oy} = 5.2 m / s

v = 15.87 m / s ,   θ = 19.1

Explanation:

This is a projectile launch problem. The horizontal speed that is constant throughout the entire path is worth 15 m / s, instead the vertical speed changes in value due to the acceleration of gravity, let's look for the initial vertical speed

                      Vy² =v_{oy}² - 2 g y

                      v_{oy}² = v_{y}² + 2 g y

                       v_{oy} = √ (v_{y}² + 2 gy

Let's calculate

                    v_{oy} = √ (1.25² + 2 9.8 1.3)

                    v_{oy} = √ (27.04)

                    v_{oy} = 5.2 m / s

 The initial speed can be calculated by the initial speed

                   v = √ v₀ₓ² + v_{oy}²

                   v = RA (15² + 5.2²)

                   v = 15.87 m / s

We look for the angle with trigonometry

                 tan θ = voy / vox

                 θ = tan⁻¹ I'm going / vox

                θ = tan⁻¹ 5.2 / 15

                θ = 19.1

The answer is

              v₀ₓ = 15 m / s

              v_{oy} = 5.2 m / s

5 0
2 years ago
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