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3 years ago

A young athlete has a mass of 42 kg. On a day when there is no wind she runs a 100m race in 14.2

Physics

1 answer:

Cloud [144]3 years ago

3 0

Answer:

7 m/s approx

Explanation:

Step one:

Given data

Mass m= 42kg

distance covered= 100m

time taken = 14.2 seconds

Required

The speed of the athlete

Step two:

We know that speed= distance/time

Substitute

Speed= 100/14.2

Speed= 7.04 m/s

Speed= 7 m/s approx

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A 6 kilogram block in outer space is moving at -100 m/s (to the left). It suddenly experiences three forces as shown below (in t

Blizzard [7]

Answer:

x = 1474.9 [m]

Explanation:

To solve this problem we must use Newton's second law, which tells us that the sum of forces must be equal to the product of mass by acceleration.

We must understand that when forces are applied on the body, they tend to slow the body down to stop it.

So as the body continues to move to the left, it is slowing down. Therefore we must calculate this deceleration value using Newton's second law. We must perform a sum of forces on the x-axis equal to the product of mass by acceleration. With leftward movement as negative and rightward forces as positive.

ΣF = m*a

$10 +12*sin(60)= - 6*a\\a = - 3.39[m/s^{2}]$

Now using the following equation of kinematics, we can calculate the distance of the block, before stopping completely. The initial speed must be 100 [m/s].

$v_{f}^{2} =v_{o}^{2}-2*a*x$

where:

Vf = final velocity = 0 (the block stops)

Vo = initial velocity = 100 [m/s]

a = - 3.39 [m/s²]

x = displacement [m]

$0 = 100^{2}-2*3.39*x\\x=\frac{10000}{2*3.39}\\x=1474.9[m]$

4 0

2 years ago

Consider an elevator with a table and a book on top of the table. The mass of the table is 10kg and the mass of the book is 2kg.

Step2247 [10]

Newton's second law allows us to find the force of the block on the table is 126 N

Newton's second law says that the net force is proportional to the product of the mass and the acceleration of the body

Σ F = m a

Where the bold letters indicate vectors, m is the mass and the acceleration of the body

A free body diagram is a diagram where the forces are represented without the details of the bodies, in the attached we can see a free body diagram of the system.

Let's start by finding the acceleration of the elevator with kinematics

v = v₀ + a t

a = $\frac{v-v_o}{a}$

Where v and v₀ are the current and initial velocity, respectively, at acceleration and t is the time

a = $\frac{8-1}{2}$

a = 3.5 m / s²

Let's write Newton's second law for each body

The book

N₂ - W₂ + N₁ = m a

Table

N₁ - W₁ - W₂ = M a

W₁ = Mg

W₂ = mg

N₁ = (M + m) g + M a

N₁ = (10 + 2) 9.8 + 10 3.5

N₁ = 152.6 N

This is the reaction of the earth to the support of the block and the table

N₂ = ma + m g - N₁

N₂ = m ( a +g) - N₁

N₂ = 2 (3.5 + 9.8) - 152.6

N₂ = 26.6 - 152.6

N₂ = -126 N

The negative sign indicates that the direction is opposite to the one assigned, this is the action of the block on the table.

In conclusion using Newton's second law we can find the forces of the block on the table is 126 N

Learn more here: brainly.com/question/19860811

4 0

2 years ago

Sometimes the tar of a newly paved road gets sticky on a very hot summer day. What causes this?

Ksivusya [100]

I’m pretty sure it is caused by the heat of the sun warming it up back into its original state of tar

6 0

3 years ago

According to Coulomb's law, what happens to the attraction of two oppositely charged objects as their distance of separation inc

NARA [144]

Answer:

Option B. Decreases

Explanation:

Coulomb's law states that:

F = Kq₁q₂ / r²

Where:

F => is the force of attraction between two charges

K => is the electrical constant.

q₁ and q₂ => are the two charges

r => is the distance apart.

From the formula:

F = Kq₁q₂ / r²

The force of attraction (F) is inversely proportional to the square of their separating distance (r).

This implies that as the distance between them increase, the force of attraction between the two charges will decrease and as the distance between two charges decrease, the force of attraction between them will increase.

Considering the question given above and the illustration given above, the force of attraction will decrease as their distance of separation increases.

Option B gives the right answer to the question.

7 0

3 years ago

A vertical spring stretches 3.4 cm when a 12-g object is hung from it. The object is replaced with a block of mass 26 g that osc

Mariulka [41]

Answer:

Period of motion is approximately 0.5447 seconds

Explanation:

We start by calculating the constant "k" of the spring which can be derived from the fact that an object of mass 12 g produced a stretch of 3.4 cm: (we write everything in SI units)

F = k * x

0.012 kg * 9.8 m/s^2 = k 0.034 m

k = 0.012 kg * 9.8 m/s^2 / (0.034 m)

k = 3.46 N/m

now we use the formula for the period (T) of a spring of constant k with a hanging mass 'm':

$T=2\pi\,\sqrt{\frac{m}{k} }$

which in our case becomes:

$T=2\pi\,\sqrt{\frac{0.026}{3.46} } \approx 0.5447\,\,sec$

4 0

3 years ago