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Nadya [2.5K]
2 years ago
11

A majorette in the Rose Bowl Parade tosses a baton into the air with an initial angular velocity of 2.5 rev/s. If the baton unde

rgoes a constant acceleration while airborne of 0.2 rev/s2 and its angular velocity is 0.8 rev/s when the majorette catches it, how many revolutions does it make in the air?
Physics
1 answer:
oksian1 [2.3K]2 years ago
4 0

Answer:

14 rev

Explanation:

w_{o} = initial angular velocity = 2.5 revs⁻¹

w = final angular velocity = 0.8 revs⁻¹

\alpha = Angular acceleration = - 0.2 revs⁻²

\theta = Angular displacement

Using the equation

w^{2} = w_{o}^{2} + 2 \alpha \theta\\0.8^{2} = 2.5^{2} + 2 (- 0.2) \theta\\ \theta = 14 rev

So the number of revolutions are 14

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B. A hydraulic jack has a ram of 20 cm diameter and a plunger of 3 cm diameter. It is used for lifting a weight of 3 tons. Find
lozanna [386]

Answer:

option (b)

Explanation:

According to the Pascal's law

F / A = f / a

Where, F is the force on ram, A be the area of ram, f be the force on plunger and a be the area of plunger.

Diameter of ram, D = 20 cm, R = 20 / 2 = 10 cm

A = π R^2 = π x 100 cm^2

F = 3 tons = 3000 kgf

diameter of plunger, d = 3 cm, r = 1.5 cm

a = π x 2.25 cm^2

Use Pascal's law

3000 / π x 100 = f / π x 2.25

f = 67.5 Kgf

4 0
2 years ago
Levi observed properties of four different waves and recorded observations about each one in his chart. A 2-column table with 4
makvit [3.9K]

Answer:

Wave W is a sound wave, Waves X and Y are light waves, and it is impossible to tell what kind of wave Wave Z is.

Explanation:

W      travels fastest through metal

X       travels fastest through air,

Y       travels more slowly through water than air    

Z       travels more slowly at cool temperatures

W appears to be sound wave  as sound travels fastest through metal .

X appears to be light wave as light travels fastest in air .

Y also appears to be light wave as  speed of light is reduced when it passes from air to water .

Z  It is impossible to tell anything about the nature of Z wave .

5 0
2 years ago
Read 2 more answers
Students use a stretched elastic band to launch carts of known mass horizontally on a track. The elastic bands exert a force F,
rodikova [14]

Answer:

the correct answer is  E

A graph of the cart's maximum speed squared as a function of x^3

Explanation:

For this exercise let's use Newton's second law

        F = m a

force has the form

        F = k x²

and acceleration is related to velocity

        a = dv / dt

Let's use the chain rule or L'Hospital

        a = dv /dx   dx/dt

        a = dv /dx    v

let's substitute

     k x² = m v dv / dx

     k /m x² dx = v dv

we integrate

     k /m    x³ /3 = v² / 2

     v² = (2k /3m)   x³

This is the expression for the variation of the speed as a function of the position, to make a linear graph realism the changes of variable

      y = v²

     x´ = x³

       y = (2k/3m)  x´

if we graph y vs x 'we have a linear graph whose slope is

      m = 2k / 3m

By reviewing the different answers, the correct answer is  E

4 0
2 years ago
A bulldozer does 4,500 J of work to push a mound of soil to the top of a ramp that is 15 m high. The ramp is at an angle of 35°
spin [16.1K]

<em>Answer</em>


Force = 170 N



<em>Explanation</em>

First find the distance (d) travelled by the bulldozer.


Sin 35 = 15/d

d = 15/(sin 35)

= 26.15m


Now;

work done = force × distance.


4500 J = force × 26.15


dividing both sides by 26.15,


Force = 4500/26.15

= 172.07 N


Answer to two significant figures = 170 N

3 0
2 years ago
Read 2 more answers
A helicopter pulls upward by means of a rope on a 250 kg crate to lift it UNIFORMLY. What is the net force on the crate?
Cloud [144]

Answer:

The net force = 0

Explanation:

The given information includes;

The mass of the crate = 250 kg

The way the helicopter lifts the crate = Uniformly (constant rate (speed), no acceleration)

In order to pull the crate upwards, the helicopter has to provide a force equivalent to the weight of the crate keeping the helicopter on the ground.

The weight of the crate = The mass of the crate × The acceleration due gravity acting on the crate

The weight of the crate, F_w↓ = 250 kg × 9.81 m/s² = 2,452.5 N

The force the helicopter should provide to just lift the crate, F_{(helicopter)}↑ = The weight of the crate = 2,452.5 N

The net force, F_{(net)} = F_{(helicopter)}↑ - F_w↓ = 2,452.5 N - 2,452.5 N = 0

The net force = 0.

3 0
2 years ago
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