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3 years ago

Using definitions and examples compare chemical and physical changes.

1 answer:

8 0

"There are several differences between a physical and chemical change in matter or substances. A physical change in a substance doesn't change what the substance is. In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed."

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A sailboat is traveling to the right when a gust of wind causes the boat to accelerate leftward at 2.5m/s2 for 4s. After t

Ber [7]

Answer:

+7.0 m/s

Explanation:

Let's take rightward as positive direction.

So in this problem we have:

a = -2.5 m/s^2 acceleration due to the wind (negative because it is leftward)

t = 4 s time interval

v = -3.0 m/s is the final velocity (negative because it is leftward)

We can use the following equation:

v = u + at

Where u is the initial velocity

We want to find u, so if we rearrange the equation we find:

$u = v - at = (-3.0 m/s) - (-2.5 m/s^2)(4 s)=+7.0 m/s$

and the positive sign means the initial direction was rightward.

6 0

3 years ago

What force must act on a 50.0-kg mass to give it an ancceleration of 0.30 m/s^2?

ratelena [41]

Answer:

15.0 N

Explanation:

see pic

3 0

2 years ago

how much gravitational potential energy do you give a 70 kg person when you lift him up 3 m in the air?

SCORPION-xisa [38]

Given gravitational potential energy when he's lifted is 2058 J.

Kinetic energy is transferred to the person.

Amount of kinetic energy the person has is -2058 J

velocity of person = 7.67 m/s².

<h3>Explanation:</h3>

Given:

Weight of person = 70 kg

Lifted height = 3 m

1. Gravitational potential energy of a lifted person is equal to the work done.

$PE_g=W=m\times g\times h\\Acceleration due to gravity = g = 9.8 \ m/s^2 \\PE_g= m = m\times g\times h= 70\times 9.8 \times 3 = 2058\ kg.m/s^2 = 2058\ J$

Gravitational potential energy is equal to 2058 Joules.

2. The Gravitational potential energy is converted into kinetic energy. Kinetic energy is being transferred to the person.

3. Kinetic energy gained = Potential energy lost = $-PE_g = -2058\ kg.m/s^2$

Kinetic energy gained by the person = (-2058 kg.m/s²)

4. Velocity = ?

Kinetic energy magnitude= $\frac{1}{2} m\times v^2 = m\times g \times h$

Solving for v, we get

$v=\sqrt{2gh} =\sqrt{2\times 9.8 \times 3} = \sqrt{58.8} = 7.67 m/s^2$

The person will be going at a speed of 7.67 m/s².

4 0

3 years ago

Describe three possible careers in physical science

Amanda [17]

Answer:

physical sicence boilagiy sxcience and earth science

Explanation:

6 0

3 years ago

.3.3: Populating a vector with a for loop. Write a for loop to populate vector userGuesses with NUM_GUESSES integers. Read integ

Reptile [31]

Answer:

#include <iostream>

#include <vector>

using namespace std;

int main() {

const int NUM_GUESSES = 3;

vector<int> userGuesses(NUM_GUESSES);

int i = 0;

int uGuess = 0;

for(i = 0; i <= userGuesses.size() - 1; i++){

cin >> uGuess;

userGuesses.at(i) = uGuess;

}

cout << endl;

return 0;

}

Explanation:

First inbuilt library were imported. Then inside the main( ) function, 3 was assigned to NUM_GUESSES meaning the user is to guess 3 numbers. Next, a vector was defined with a size of NUM_GUESSES.

Then a for-loop is use to receive user guess via cin and each guess is assigned to the vector.

8 0

3 years ago