GGRB13H3 Lecture : Shetal Singh

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skywallaby661

26 Apr 2012

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Human/ human geographies through three case studies: bee and the military, mosquitoes, cats. Social geography has to do with the relationship between people and place and the relationship between structure and agency. How does animals play a role, when we make humans the centre of everything. Humanity emerges through nature rather than out of it. Argument is that we need new theories to answer these questions. Organizations made up of nonhuman actors that regulate contain and enable the practices of human body. For example a circle desk in the office, it plays a role to show power. It doesn"t mean that it is beyond human but offers a way to conceptualize the world objects and technologies. Things and creatures play a huge role in our lives, for example a dog. Says where you are in the world affects the way you look.

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2. Which of the following statements accurately describe the relationship between science and technology?

⬤ Technology and science are the same thing, and achieve the same goals.

⬤ The knowledge gained from science helps humans develop technology.

⬤ Improvements in technology can allow for better scientific observations.

⬤ Science and technology both use the scientific method answer questions.

⬤ Technology allows scientists to avoid using the scientific method.

mariabran12

I am so lost onwere to even begin. I just need help trying to find the Ñ² (angle)for part part 1 of the experiment if anyone can just explain how todo that and maybe give me a step-by-step example so I can finishthe rest. Thank you! Experiment 6 ~ Friction

Purpose:

In this lab, you will make some basic measurements of friction.You will measure the coefficients of staticfriction between several combinations of surfaces using aninclined plane, and you will measure the coefficient ofkinetic friction between two of the combinationsof surfaces you used in the static friction part of thisexperiment.

Part 1: StaticFriction

Theory:

The coefficient of static frictionm_s can be measured experimentally foran object placed on an inclined plane (a.k.a. ramp, a.k.a. hill).The coefficient of static friction is related to the criticalangle q_c for the ramp, at whichthe object just begins to slide. Using what we havecovered in class, you can derive this relationshipyourself! At this critical angle, static friction preventing theobject from sliding down the hill is just exactly equal to thecomponent of the objectâs weight along the hill. If the componentof the weight along the hill were just a little greater, it wouldovercome friction, and the object would start to slide down. Thefree body diagram for this situation will look like the figuresketched below. Use this diagram to find an equation that relatesm_s toq_c.

Questions:

1. How do the values of m_s compareto the values of m_k? (Of course, youcan only compare them for the same pairs of materials.)

2. Is the relationship betweenm_sand m_kwhat you expected?

3. Of the two parts of the experiment, measurement ofm_sand measurement ofm_k, which had more sources of error?What were some of the sources of error?

4. Could m_k orm_s ever be greater than 1? Explain whyor why not.

5. Is the coefficient of friction the same as when the block wasstanding on its larger (or smaller) end?

6. Think about your results. Do they make sense when youconsider your everyday experiences?

This problem introduces the concept of tension. The example is a rope, oriented vertically, that is being pulled from both ends. Let F_u and F_d (with u for up and d for down) represent the magnitude of the forces acting on the top and bottom of the rope, respectively. Assume that the rope is massless so that its weight is negligible compared with the tension. (This is not a ridiculous approximation-modern rope material such as Kevlar can carry tensions thousands of times greater than the weight of tens of meters of such rope.)

Consider the three sections of rope labeled a, b, and c in the figure.

At point 1, a downward force of magnitude F_ad acts on section a.
At point 1, an upward force of magnitude F_bu acts on section b.
At point 1, the tension in the rope is T₁.
At point 2, a downward force of magnitude F_bd acts on section b.
At point 2, an upward force of magnitude F_cu acts on section c.
At point 2, the tension in the rope is T₂.

(A) What is the magnitude F_ad of the downward force on section a?

(B) What is the magnitude F_bu of the upward force on section b?

(C) The magnitude of the upward force on c, F_cu, and the magnitude of the downward force on b, F_bd, are equal because of which of Newton's laws?

(D) The magnitude of the force F_bu is ______ F_bd.

(E) Now consider the forces on the ends of the rope. What is the relationship between the magnitudes of these two forces?

(a) F_u > F_d

(b) F_u = F_d

(F) The ends of a massless rope are attached to two stationary objects (e.g., two trees or two cars) so that the rope makes a straight line. For this situation, which of the following statements are true?

(a) The tension in the rope is everywhere the same.

(b) The magnitudes of the forces exerted on the two objects by the rope are the same.

(d) The forces exerted on the two objects by the rope must be in the direction of the rope.

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GGRB13H3 Lecture : Shetal Singh

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