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Jlenok [28]
3 years ago
14

A student drops a 1.5 kg rock off of a 4.0 m tall bridge. The speed of the rock just before it hits the water below is 6 m/s. Ho

w much energy was lost due to air resistance?
Physics
2 answers:
olga nikolaevna [1]3 years ago
8 0

Answer:

Energy due to air resistance = 31.8 Joules

Explanation:

According to the law of conservation of energy, energy can neither be created nor destroyed but can be transformed from one form to another

Kinetic Energy + Energy due to air resistance = Potential energy..........(1)

If there is no energy loss due to air resistance, potential energy = kinetic energy

mass, m = 1.5 kg

height, h = 4.0 m

speed, v = 6 m/s

Kinetic energy = 0.5 mv²

Kinetic energy = 0.5 * 1.5 * 6²

Kinetic energy = 27 Joules

Potential Energy = mgh

Potential energy = 1.5 * 9.8 * 4

Potential energy = 58.8 Joules

From equation (1)

27 + Energy due to air resistance = 58.8

Energy due to air resistance = 58.8 - 27

Energy due to air resistance = 31.8 Joules

Brilliant_brown [7]3 years ago
5 0

Answer:

Explanation:

Note:

Air resistance in the way means not all of the potential energy can be converted to kinetic energy.

Given:

Mass = 1.5 kg

D = 4 m

Vf = 6 m/s

Energy + KE = PE

= (M × g × d) - (1/2 × M × V^2)

= (1.5 × 9.8 × 4) - (1/2 × 1.5 × 6^2)

= 58.8 - 27

= 31.8 J

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a solution made by dissolving 116 g of CaCl2 in 64 g of water has a density of 1.180 g/ml at 20 degrees celsius what is the mola
Makovka662 [10]

Answer:

The molarity of CaCl2 in the solution is 4.94 M

Explanation:

First of all you need to calculate CaCl2 mass.

You have one atom of Ca = 40.07 g/mol and two atoms of Cl = 35.45 g/mol so the molecule has a mass of 110.97 g/mol.

Now, knowing that your solution will have a mass of 64 grams of water + 116 grams of CaCl2 = 180 grams, you can calculate its volume, knowing that density = mass/volume

density x mass = volume --> 1,180 g/ml x 180 g = 212.4 ml

In 212.4 ml, you have 116 grams of CaCl2. You can calculate how many moles of CaCl2 you have:

110.97 g ------ 1 mol

116 g -------- x = (116 g x 1 mol) / 110.97 g =  1.05 moles

The molarity in a solution equals how many moles of a certain solute you have in 1000 ml of solution. In this solution, you have 1.05 moles in 212.4 ml, so in 1000 ml you will have:

212.4 ml ------- 1.05 moles

1000 ml -------- x = (1000 ml x 1.05 moles) / 212.4 ml = 4.94 moles.

This means the molarity of CaCl2 in the solution is 4.94 M.

4 0
3 years ago
What are possible units for impulse? Check all that apply. kg • m kg • N • s N • m
Vlada [557]

We know that impulse is simply the product of Force and time:

Impulse = Force * time

 

Since Force has a unit of Newton or kg m/s^2 and time is in seconds, therefore impulse can have units as:

N s

or

<span>kg m/s</span>

4 0
3 years ago
Jessica stretches her arms out 0.60 m from the center of her body while holding a 2.0 kg mass in each hand. She then spins aroun
Juliette [100K]

Answer:

a.) L = 2.64 kgm^2/s

b.) V = 4.4 m/s

Explanation: Jessica stretches her arms out 0.60 m from the center of her body. This will be considered as radius.

So,

Radius r = 0.6 m

Mass M = 2 kg

Velocity V = 1.1 m/s

Angular momentum L can be expressed as;

L = MVr

Substitute all the parameters into the formula

L = 2 × 1.1 × 0.6 = 1.32kgm^2s^-1

the combined angular momentum of the masses will be 2 × 1.32 = 2.64 kgm^2s-1

b. If she pulls her arms into 0.15 m,

New radius = 0.15 m

Using the same formula again

L = 2( MVr)

2.64 = 2( 2 × V × 0.15 )

1.32 = 0.3 V

V = 1.32/0.3

V = 4.4 m/s

Her new linear speed will be 4.4 m/s

4 0
3 years ago
HELP PLEASE I need to finish this asap
ELEN [110]

Answer:

I'm not 100% sure, but I think the answer would be the first one because there's a force pushing the object in every direction, so they would cancel eachother out and make the object stay in the same place.

Explanation:

pls vote brainliest

6 0
2 years ago
Read 2 more answers
What is the mass of an atom that has 4 protons, 5 neutrons, and 4 electrons? Please explain. This is a final exam question. Plea
12345 [234]

Answer:

9

Explanation:

You get this answer by adding the protons and neutrons together.

5 0
3 years ago
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