4. What is the purpose of the corneal reflex?

In a lab experiment, two identical gliders on an air track are held together by a piece of string, compressing a spring between

ddd [48]

Answer:

Part a)

$v_2 = -0.300$

Part b)

Here final kinetic energy is more than the initial kinetic energy

This increase in kinetic energy is due to spring connected between them as the spring energy is converted into kinetic energy of two blocks

Explanation:

Part a)

As we know that there is no external force on the system of two gliders

So here we can use momentum conservation for two gliders

So we will have

$m_1 v_1 + m_2 v_2 = (m_1 + m_2)v_i$

$m_1 = m_2$

$1.300 + v_2 = 2(0.500)$

$v_2 = -0.300$

Part b)

now we will have

initial kinetic energy of both gliders is given as

$K_i = \frac{1}{2}(m + m)(0.500)^2$

$K_i = 0.25m$

Final kinetic energy of two gliders

$K_f = \frac{1}{2}m(0.300)^2 + \frac{1}{2}m(1.300)^2$

$K_f = 0.89 m$

so here final kinetic energy is more than the initial kinetic energy

This increase in kinetic energy is due to spring connected between them as the spring energy is converted into kinetic energy of two blocks

8 0

3 years ago

Usain Bolt, a Jamaican sprinter, holds the Olympic and world records for the 100-m and 200-m dash, which he

stellarik [79]

Answer: 10.36m/s

How? Just divide 200m by 19.3 and you will get how fast he ran per m/s

6 0

3 years ago

A large crate with mass m rests on a horizontal floor. The static and kinetic coefficients of friction between the crate and the

Mariana [72]

a) $F=\frac{\mu_k mg}{cos \theta - \mu_k sin \theta}$

Here the crate is moving at constant velocity, so no acceleration:

a = 0

Let's analyze the forces acting along the horizontal and vertical direction.

- Vertical direction: the equation of the forces is

$R-Fsin \theta - mg = 0$ (1)

where

R is the normal reaction of the floor (upward)

$F sin \theta$ is the component of the force F in the vertical direction (downward)

mg is the weight of the crate (downward)

- Horizontal direction: the equation of the forces is

$F cos \theta - \mu_k R = 0$ (2)

where

$F cos \theta$ is the horizontal component of the force F (forward)

$\mu_k R$ is the force of friction (backward)

From (1) we get

$R=Fsin \theta +mg$

And substituting into (2)

$F cos \theta - \mu_k (Fsin \theta +mg) = 0\\F cos \theta -\mu _k F sin \theta = \mu_k mg\\F(cos \theta - \mu_k sin \theta) = \mu_k mg\\F=\frac{\mu_k mg}{cos \theta - \mu_k sin \theta}$

b) $\mu_s=cot(\theta)$

In this second case, the crate is still at rest, so we have to consider the static force of friction, not the kinetic one.

The equations of the forces will be:

$R-Fsin \theta - mg = 0$ (1)

$F cos \theta - \mu_s R = 0$ (2)

In this second case, we want to find the critical value of $\mu_s$ such that the woman cannot start the crate: this means that the force of friction must be at least equal to the component of the force pushing on the horizontal direction, $F cos \theta$ .

Therefore, using the same procedure as before,

$R=Fsin \theta +mg$

$F cos \theta - \mu_s (Fsin \theta +mg) = 0$

And solving for $\mu_s$ ,

$F cos \theta = \mu_s (Fsin \theta +mg) \\\mu_s = \frac{F cos \theta}{F sin \theta + mg}$

Now we analyze the expression that we found. We notice that if the force applied F is very large, $F sin \theta >> mg$ , therefore we can rewrite the expression as

$\mu_s \sim \frac{F cos \theta}{F sin \theta}\\\mu_s=cot(\theta)$

So, this is the critical value of the coefficient of static friction.

8 0

3 years ago

PLEASE HELP!! DUE IN 40 MINUTES!!

Irina18 [472]

A frame of reference can be thought of as the state of motion of the observer of some event. For example, if you're sitting on a lawn chair watching a train travel past you ... you could even watch a glass of water sitting on a table inside the train move ... This seems like a simple and obvious example, yet when you take a step

6 0

3 years ago

Wireless Internet networks, including many used in homes, often make use of high-frequency radio waves. High-frequency waves are

lutik1710 [3]

The answer is d , small disruptions

4 0

3 years ago

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4. What is the purpose of the corneal reflex?​

4. What is the purpose of the corneal reflex?