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Llana [10]
3 years ago
14

Pls ans 10 no. From laws of motion

Physics
1 answer:
Vlad1618 [11]3 years ago
4 0

Answer:

40N

Explanation:

Since both weights are connected to one string, you can say that the tensions above each are equal to each other.

If you do the sum of forces for the 4kg mass, then the tension comes out to 40N (if we take gravity to be 10m/s²). But that seemed too good to be true, so I decided to do the work for the 7kg mass as well [which included finding the normal force (N) and plugging it into the sum of forces for the 7kg mass] to find that it also gives 40N as the answer.

If I were to put my process into steps:

  1. Write out the sum of Forces for both masses
  2. Set them equal to each other to find normal force (because this is the only unknown)
  3. Calculate and compare the two tensions to see if they are equal

*This all seems to line up perfectly, but do let me know if my answer doesn't match up with what you might find to he the answer later on.

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What is the energy of a rock with a mass of 10.2 kg on a cliff that is 300 m height?
Anuta_ua [19.1K]

The potential energy of the rock is 30,000 J

Explanation:

The mechanical energy of an object is equal to the sum of its gravitational potential energy (PE) and its kinetic energy (KE):

E=PE+KE

where

PE is the gravitational potential energy, which is the energy possessed by the object due to its position in the gravitational field

KE is the kinetic energy, which is the energy possessed by the object due to its motion

In this problem, the rock is at rest, so its kinetic energy is zero:

KE = 0

Therefore, the energy of the rock is just equal to its potential energy, which is:

E=PE=mgh

where

m = 10.2 kg is the mass of the rock

g=9.8 m/s^2 is the acceleration of gravity

h = 300 m is the height of the rock above the ground

Substituting and solving, we find

PE=(10.2)(9.8)(300)=30,000 J

Learn more about potential energy:

brainly.com/question/1198647

brainly.com/question/10770261

#LearnwithBrainly

4 0
3 years ago
An aluminum bar 600mm long, with diameter 40mm long has a hole drilled in the center of the bar.The hole is 30mm in diameter and
Svetradugi [14.3K]

Answer:

Total contraction on the Bar  = 1.22786 mm

Explanation:

Given that:

Total Length for aluminum bar = 600 mm  

Diameter for aluminum bar  = 40 mm

Hole diameter  = 30 mm

Hole length = 100 mm

elasticity for the aluminum is 85GN/m² = 85 × 10³ N/mm²

compressive load P = 180 KN = 180  × 10³ N

Calculate the total contraction on the bar = ???

The relation used in  calculating the contraction on the bar is:

\delta L = \dfrac{P *L }{A*E}

The relation used in  calculating the total contraction on the bar can be expressed as :

Total contraction in the Bar = (contraction in part of bar without hole + contraction in part of bar with hole)

i.e

Total contraction on the Bar = \dfrac{P *L_1 }{A_1*E} +  \dfrac{P *L_2 }{A_2 *E}

Let's find the area of cross section without the hole and with the hole

Area of cross section without the hole is :

Using A = πd²/4

A = π (40)²/4

A = 1256.64 mm²

Area of cross section with the hole is :

A = π (40²-30²)/4

A = 549.78 mm²

Total contraction on the Bar = \dfrac{P *L_1 }{A_1*E} +  \dfrac{P *L_2 }{A_2 *E}

Total contraction on the Bar  = \dfrac{180 *10^3 \N  }{85*10^3 \ N/mm^2} [\dfrac{500}{1256.64}+ \dfrac{100}{549.78}]

Total contraction on the Bar  = 2.117( 0.398 + 0.182)

Total contraction on the Bar  = 2.117*(0.58)

Total contraction on the Bar  = 1.22786 mm

5 0
4 years ago
A 2-kg book falls off a shelf. It hits a student traveling 2 m/s. How much kinetic energy does the book have?
Gekata [30.6K]

4 J

1/2 mv^2 is ke formula

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What is not changed when work is done by a machine?
Irina18 [472]
B) The amount of work done
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If you could live any where except for where you are now where would you live
laila [671]

Answer:

I would live in the Atlantic ocean on a lux liner

Explanation:

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3 years ago
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