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Alekssandra [29.7K]

2 years ago

10

A sound wave increases in pitch. Which of the following changes has occurred?

1 answer:

statuscvo [17]2 years ago

6 0

<span>If the pitch of a sound increased, then the wave frequency increased. (D)</span>

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What part causes the disc brake caliper piston to retract when the brakes are released?

Orlov [11]

The part that causes the disc caliper piston to retract when the brakes are released is the square-cut O-ring.
The square cut seal is the most important part of a disc brake caliper, for keeping the brake behind the piston so that when you step on the brake pedal, it releases a pressure that applied to the piston which in return applies the pad to the rotor.

3 0

2 years ago

Two kids are playing on a newly installed slide, which is 3 m long. John, whose mass is 30 kg, slides down into William (20 kg),

yuradex [85]

Answer:

$v=3.564\ m.s^{-1}$

$\Delta v =2.16\ m.s^{-1}$

Explanation:

Given:

mass of John, $m_J=30\ kg$

mass of William, $m_W=30\ kg$

length of slide, $l=3\ m$

(A)

height between John and William, $h=1.8\ m$

<u>Using the equation of motion:</u>

$v_J^2=u_J^2+2 (g.sin\theta).l$

where:

v_J = final velocity of John at the end of the slide

u_J = initial velocity of John at the top of the slide = 0

Now putting respective :

$v_J^2=0^2+2\times (9.8\times \frac{1.8}{3})\times 3$

$v_J=5.94\ m.s^{-1}$

<u>Now using the law of conservation of momentum at the bottom of the slide:</u>

<em>Sum of initial momentum of kids before & after collision must be equal.</em>

$m_J.v_J+m_w.v_w=(m_J+m_w).v$

where: v = velocity with which they move together after collision

$30\times 5.94+0=(30+20)v$

$v=3.564\ m.s^{-1}$ is the velocity with which they leave the slide.

(B)

frictional force due to mud, $f=105\ N$

<u>Now we find the force along the slide due to the body weight:</u>

$F=m_J.g.sin\theta$

$F=30\times 9.8\times \frac{1.8}{3}$

$F=176.4\ N$

<em><u>Hence the net force along the slide:</u></em>

$F_R=71.4\ N$

<em>Now the acceleration of John:</em>

$a_j=\frac{F_R}{m_J}$

$a_j=\frac{71.4}{30}$

$a_j=2.38\ m.s^{-2}$

<u>Now the new velocity:</u>

$v_J_n^2=u_J^2+2.(a_j).l$

$v_J_n^2=0^2+2\times 2.38\times 3$

$v_J_n=3.78\ m.s^{-1}$

Hence the new velocity is slower by

$\Delta v =(v_J-v_J_n)$

$\Delta v =5.94-3.78= 2.16\ m.s^{-1}$

8 0

2 years ago

A 20-lb force acts to the west while an 80-lb force acts 45° east of north. The magnitu 80 lb 70 lb 067 lb 100 lb

natulia [17]

Answer:

option C

Explanation:

given,

force act on west = 20 lb

force act at 45° east of north = 80 lb

magnitude of force = ?

∑ F y = 80 cos 45⁰

F y = 56.57 lb

magnitude of forces in x- direction

∑ F x = -20 + 80 sin 45⁰

= 36.57 lb

net force

F = $\sqrt{F_x^2+F_y^2}$

F = $\sqrt{56.57^2+36.57^2}$

F = 67.36 lb≅ 67 lb

hence, the correct answer is option C

4 0

2 years ago

What would a series circuit be used for?

igor_vitrenko [27]

Answer:

C

Explanation:

a series circuit would be an odd choice to power a battery or light a lamp when a direct would be much more efficient, and it's not converting types of energy, so C is the best possible answer

6 0

2 years ago

Which feature of a chemical equation represents the law of conservation of mass?

N76 [4]

Answer:

it shows the products of a chemical reaction to the right of the reaction arrow

4 0

2 years ago