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vampirchik [111]
2 years ago
11

Corey, whose mass is 95 kg, stands on a bathroom scale in an elevator. The scale reads 850 N for the first 3.0 s after the eleva

tor starts to move, then 930 N for the next 3.0 s.What is the elevator's velocity 4.0 s after starting?
Physics
1 answer:
lyudmila [28]2 years ago
7 0

Answer:

v₂ = 2.568 m/s

Explanation:

given,

mass of Corey = 95 Kg

reading of sale for first 3 s when elevator start to move = 850 N

scale reading for the next 3.0 s = 930 N

Gravitation force acting =

  F = m g

  F = 95 x 9.8

  F = 931 N

using newtons second law, due to movement of elevator

    F_{net} = m a

 W - N = m a₁

931- 850 = 95 x a₁

    a₁ = 0.852 m/s²

now,

velocity calculation

v₁ = a₁t

v₁ = 0.852 x 3 = 2.557 m/s

now, For second case

931 - 930 = 95 x a₂

a₂ = 0.011 m/s²

now, velocity after 4 s

v₂ = v₁ + a₂ t

v₂ = 2.557+ 0.011 x (4 - 3)

(4-3) because velocity after 3 second is calculate we need to calculate velocity after 4 s from beginning.

v₂ = 2.557 + 0.011

v₂ = 2.568 m/s

velocity of the elevator is equal to v₂ = 2.568 m/s

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puteri [66]

Answer:

A) vertically upward

Explanation:

Since the tyre is rotating with uniform angular speed and moving with constant linear speed

So as soon as a small stone is stuck into the groove of the tyre the speed of the stone is same as that of the tyre

so now we can say that stone will start revolving with the tyre of the car at constant angular speed and moving with uniform speed also

so here just after that the tangential acceleration of the stone must be zero while radial acceleration must be towards the center of the tyre given as

a_c = \omega^2 R

so we will have direction of net acceleration is towards its center so correct answer will be

A) vertically upward

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2 years ago
John is carrying a shovelful of snow. The center of mass of the 3.00 kg of snow he is holding is 15.0 cm from the end of the sho
Andru [333]

Answer:

James is correct here as the force of hand pushing upwards is always more than the force of hand pushing down

Explanation:

Here we know that one hand is pushing up at some distance midway while other hand is balancing the weight by applying a force downwards

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then for that force we can say that net torque must be balanced

so here we have

F_{down} L_1 = W_{snow} L_2

so here we have

F_{down} = \frac{L_2}{L_1} (W_{snow})

so here we can say that upward force by which we push up is always more than the downwards force

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2 years ago
Platinum has a density of 21.4 g/cm3. if thieves were to steal platinum from a bank using a small truck with a maximum payload o
slega [8]
We will convert the 1dm3 in terms of cm3 as follows:

1dm^3 = (10 cm)^3
= 1000 cm^3

The mass of platinum is equal to 900 lb. 
Then we will convert the mass in terms of grams as follows:
1 lb = 453.6 g
900 = 900 x 453.6 g
= 408240 g

Then density of platinum is equal to 21.4 g/cm^3 
We will calculate the volume of platinum in mass 408240 g as follows:
Volume of platinum = mass of platinum / density of platinum
= 408240 g / 21.4 g/cm^3 
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The total volume of platinum is 19076.6 cm^3
The volume of platinum in 1 L bar is 1000cm^3
So, to calculate the number of bars we will use the formula as follows;
Number of bars = volume of platinum available / volume of platinum required in 1 L bar
= 19076.6 cm^3 / 1000 cm^3
= 19
So, the number of bars are 19.
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2 years ago
When a perfume bottle is opened, some liquid changes to gas and the fragrance spreads around the room. Which sentence explains t
monitta
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since they do not have a definite volume, this causes it to spread out in the air 
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Do as physics instructor fred cauthen does and place a tennis ball close to and above the top of a basketball. drop the balls to
Ksivusya [100]

Answer:

after shock

creating a system for the conservation of the energy of the basketball ball and creating a system for the tennis ball only, the conservation of energy should be applied to each system independently

Explanation:

When the two balls fall they acquire the same speed since they are accelerated by the same force, their weight and the acceleration of the acceleration of gravity. When reaching the floor the mechanical energy of the system is conserved.

Upon reaching the floor, the first ball (basketball) collides with the floor, this process is very fast, at the end of the process the basketball comes out with a velicad up and collides with the much lighter tennis ball that is still descending .

we assume that the shocks are elastic, when solving the momentary and kinetic energy findings, we find the velocities after each shock

     

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Here we must separate the system, creating a system for the conservation of the energy of the basketball ball and another system for the tennis ball only, the conservation of energy should be applied to each system independently

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                 h = 2 v₀²/g

To reconcile this with the conservation of energy we must calculate the energy for the tennis ball at two points, the first when the crash with the tennis ball ends and at the end point at its maximum height.

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