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4 years ago

Which statements describe friction? Check all that apply.

Physics

2 answers:

Ad libitum [116K]4 years ago

7 0

The answer is 3, 5 and 2

svp [43]4 years ago

6 0

Answer:

The answers are 2, 3 and 5

Explanation:

Frictional force is a contact force that occurs as two bodies move or slides over each other causing a reduction in efficiency and can be reduced by greasing.

2. It causes a change in motion.

3. It occurs in the same direction as the push force.

5. It is parallel to the surfaces that rub together

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Runaway truck ramps are common on mountainous highways in case the brakes fail on large trucks. If a

dusya [7]

Answer:

$W=-21,870,000\ J$

Explanation:

<u>Work and Kinetic Energy </u>

The work an object does due to its motion is equal to the change of its kinetic energy. Being ko and k1 the initial and final kinetic energy respectively and m the mass of the object, then

$W=\Delta k=k_1-k_0$

Since

$\displaystyle k=\frac{mv^2}{2}$

We have

$\displaystyle W=\frac{mv_1^2}{2}-\frac{mv_0^2}{2}$

The truck has a mass of 60,000 kg and is moving at 27 m/s. The runaway truck ramp must stop the truck, so the final speed is 0. Thus

$\displaystyle W=\frac{(60,000)0^2}{2}-\frac{(60,000)(27)^2}{2}$

$W=0-21870000\ J$

$\boxed{W=-21,870,000\ J}$

3 0

4 years ago

What role did gravity play in the formation of the planets?

joja [24]

Your answer would be D.
If an object has mass, it has gravity, and the more mass it has, the stronger its gravity. During the formation of planets, essentially, various matter and elements pulled and fused together (because of the gravity), forming planetesimals.

3 0

3 years ago

Read 2 more answers

Dwayne ‘The Rock’ Johnson needs to escape from the fourth floor of a burning building (in a movie). He ties a rope around his wa

ZanzabumX [31]

Answer:

Final Speed of Dwayne 'The Rock' Johnson = 15.812 m/s

Explanation:

Let's start out with finding the force acting downwards because of the mass of 'The Rock':

Dwayne 'The Rock' Johnson: 118kg x 9.81m/s = 1157.58 N

Now the problem also states that the kinetic friction of the desk in this problem is 370 N

Since the pulley is smooth, the weight of Dwayne Johnson being transferred fully, and pulls the desk with a force of 1157.58 N. The frictional force of the desk is resisting this motion by a force of 370 N. Subtracting both forces we get the resultant force on the desk to be: 1157.58 - 370 = 787.58 N

Now lets use F = ma to calculate for the acceleration of the desk:

787.58 = 63 x acceleration

acceleration = 12.501 m/s

Finally, we can use the motion equation:

$v^2 - u^2 = 2*a*s$

here u = 0 m/s (since initial speed of the desk is 0)

a = 12.501 m/s

and s = 10 m

Solving this we get:

$v^2 - 0 = 2 * 12.501 * 10$

$v = 15.812 m/s$

Since the desk and Mr. Dwayne Johnson are connected by a taught rope, they are travelling at the same speed. Thus, Dwayne also travels at 15.812 m/s when the desk reaches the window.

5 0

4 years ago

A karate master strikes a board with an initial velocity of 10.0 m/s, decreasing to 1.0 m/s as his hand passes through the board

kenny6666 [7]

The force exerted on the board by the karate master given the data is -4500 N

<h3>Data obtained from the question </h3>

Initial velocity (u) = 10 m/s
Final velocity (v) = 1 m/s
Time (t) = 0.002 s
Mass (m) = 1 Kg
Force (F) = ?

<h3>How to determine the force</h3>

The force exerted can be obtained as illustrated below:

F = m(v - u) / t

F = 1 (1 - 10) / 0.002

F = (1 × -9) / 0.002

F = -4500 N

Learn more about momentum:

brainly.com/question/250648

#SPJ1

6 0

2 years ago

What is the best explanation for why a magnet is different from a regular piece of metal?

arlik [135]

Answer:

in a magnet there is a magnetic field that draws ever mental to it

5 0

3 years ago