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inna [77]
3 years ago
7

Two kids create a makeshift seesaw by setting a 4-m long uniform plank on a saw horse. The saw horse is 0.5 m to the left of the

center of mass of the plank. The child of mass m1 = 42 kg sits at the left end of the plank. The child of mass m2 = 31 kg sits 1 m to the right of the center of mass of the plank. What is the mass of the plank?
Physics
1 answer:
GREYUIT [131]3 years ago
3 0

Answer:

The mass of the plank is 33 kg.

Explanation:

Given that,

Length of plank = 4 m

Distance in left from the center= 0.5 m

Mass of child = 42 kg

Mass of other child = 31 kg

Distance in right from the center= 1 m

We can sum torques around the saw horse; each force generates a torque equal to force x distance from saw horse

We need to calculate the torque for first child

Using formula of torque

\tau =mg\times d

Put the value into the formula

\tau=42\times9.8\times1.5

\tau=617.4\ N-m

We need to calculate the torque for second child

The child is 1.5 m from the saw horse

Using formula of torque

\tau' =mg\times d

Put the value into the formula

\tau'=31\times9.8\times1.5

\tau'=455.7\ N-m

The weight of the plank produces a clockwise torque

\tau''=mg\times d

\tau''=mg\times 0.5

We need to calculate the mass of the plank

Using balance equation of torque

\tau=\tau''+\tau'

Put the value into the formula

617.4=mg\times0.5+455.7

m=\dfrac{617.4-455.7}{0.5\times9.8}

m=33\ kg

Hence, The mass of the plank is 33 kg.

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3 years ago
____________ was a series of human spaceflight missions undertaken by the u.S. Devoted to the goal of landing a man on the moon
4vir4ik [10]

Answer:

The Apollo program or Project Apollo was a series of human spaceflight missions undertaken by the u.S. Devoted to the goal of landing a man on the moon and returning him to earth safely.

Explanation:

Project Apollo or Apollo program was the spaceflight program carried out by the United States of America during the years 1961-1972 using the Apollo spacecraft. This project's main goal was to land a man on the Moon and to safely return him to Earth. This goal was accomplished with the Apollo 11 moon-landing mission on July 20, 1969, when an Apollo Lunar Module (LM) landed on the Moon's surface and the astronauts Neil Armstrong and Buzz Aldrin walked on the lunar surface while Michael Collins stayed in the command and service module (CSM) in the lunar orbit. On July 24, all three astronauts landed safely on Earth.

This project included three unmanned test flights (Apollo 4 through Apollo 6) and eleven manned flights (Apollo 7 through Apollo 17). All these spaceflight missions were carried out by NASA (National Aeronautics and Space Administration) and all were launched from the Kennedy Space Center, Florida.

7 0
3 years ago
What force must the worker exert to get the box moving & what force must the worker exert to accelerate the box at 0.1 meter
photoshop1234 [79]

Since static friction is the minimum force required to just start the motion of a stationary object.

Here if we need to start an object from rest then we required F = 700 N

So for the first part of the above problem Force will be F = 700 N

Now if the box is already moving then we will have to use kinetic friction force between box and floor

now we can write the equation of net force as

F - F_k = m*a

here

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now we will have

F - 220 = 500* 0.1

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3 0
3 years ago
Two circus performers rehearse a trick in which a ball and a dart collide. Horatio stands on a platform 9.8 m above the ground a
xenn [34]

Answer:

Time = 0.55 s

Height = 8.3 m

Explanation:

The ball is dropped and therefore has an initial velocity of 0. Its acceleration, g, is directed downward in the same direction as its displacement, h_b.

The dart is thrown up in which case acceleration, g, acts downward in an opposite direction to its displacement, h_d. Both collide after travelling for a time period, t. Let the height of the dart from the ground at collision be h_d and the distance travelled by the ball measured from the top be h_b.

It follows that h_d+h_b=9.8.

Applying the equation of motion to each body (h = v_0t + 0.5at^2),

Ball:

h_b=0\times t + 0.5\times 9.8t^2 (since v_{b0} =0.)

h_b=4.9t^2

Dart:

h_d=17.8\times t - 0.5\times9.8t^2 (the acceleration is opposite to the displacement, hence the negative sign)

h_d=17.8\times t - 4.9t^2

But

h_b+h_d =9.8

17.8\times t - 4.9t^2+4.9t^2 =9.8

17.8\times t = 9.8

t = 0.55

The height of the collision is the height of the dart above the ground, h_d.

h_d=17.8\times t - 4.9t^2

h_d=17.8\times 0.55 - 4.9\times(0.55)^2

h_d=9.79 - 1.48225

h_d=8.3

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melomori [17]

Answer:

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Explanation:

<u>The Amplitude of a Wave</u>

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To calculate the amplitude from a graph, we measure the maximum point and the minimum point the wave reaches. Then we subtract both values and divide the result by 2.

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