Answer:
i dont have such a type of keyboard so, i can't solve it sorry
Answer:
B
Explanation:
If you pass white light through a blue filter, then only blue color will appear on the other end. This is because a blue filter will only allow blue light through it. And will absorb other color. In other words the rest colors would disappear. Hence the camera would receive just blue light. This phenomenon is referred to as color by subtraction.
Answer:
h >5/2r
Explanation:
This problem involves the application of the concepts of force and the work-energy theorem.
The roller coaster undergoes circular motion when going round the loop. For the rider to stay in contact with the cart at all times, the roller coaster must be moving with a minimum velocity v such that at the top the rider is in a uniform circular motion and does not fall out of the cart. The rider moves around the circle with an acceleration a = v²/r. Where r = radius of the circle.
Vertically two forces are acting on the rider, the weight and normal force of the cart on the rider. The normal force and weight are acting downwards at the top. For the rider not to fall out of the cart at the top, the normal force on the rider must be zero. This brings in a design requirement for the roller coaster to move at a minimum speed such that the cart exerts no force on the rider. This speed occurs when the normal force acting on the rider is zero (only the weight of the rider is acting on the rider)
So from newton's second law of motion,
W – N = mv²/r
N = normal force = 0
W = mg
mg = ma = mv²/r
mg = mv²/r
v²= rg
v = √(rg)
The roller coaster starts from height h. Its potential energy changes as it travels on its course. The potential energy decreases from a value mgh at the height h to mg×2r at the top of the loop. No other force is acting on the roller coaster except the force of gravity which is a conservative force so, energy is conserved. Because energy is conserved the total change in the potential energy of the rider must be at least equal to or greater than the kinetic energy of the rider at the top of the loop
So
ΔPE = ΔKE = 1/2mv²
The height at the roller coaster starts is usually higher than the top of the loop by design. So
ΔPE =mgh - mg×2r = mg(h – 2r)
2r is the vertical distance from the base of the loop to the top of the loop, basically the diameter of the loop.
In order for the roller coaster to move smoothly and not come to a halt at the top of the loop, the ΔPE must be greater than the ΔKE at the top.
So ΔPE > ΔKE at the top. The extra energy moves the rider the loop from the top.
ΔPE > ΔKE
mg(h–2r) > 1/2mv²
g(h–2r) > 1/2(√(rg))²
g(h–2r) > 1/2×rg
h–2r > 1/2×r
h > 2r + 1/2r
h > 5/2r
Phase 1. Forethought/preaction—This phase precedes the actual performance; sets the stage for action; maps out the tasks to minimize the unknown; and helps to develop a positive mindset. Realistic expectations can make the task more appealing. Goals must be set as specific outcomes, arranged in order from short-term to long-term. We have to ask students to consider the following:
<span>When will they start?Where will they do the work?How will they get started?<span>What conditions will help or hinder their learning activities are a part of this phase?
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Phase 2. Performance control—This phase involves processes during learning and the active attempt to utilize specific strategies to help a student become more successful.
We have to ask students to consider the following:
<span>Are students accomplishing what they hoped to do?Are they being distracted?Is this taking more time than they thought?Under what conditions do they accomplish the most?What questions can they ask themselves while they are working?<span>How can they encourage themselves to keep working (including self-talk—come on, get your work done so you can watch that television show or read your magazine!)
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Phase 3. Self-reflection—This phase involves reflection after the performance, a self-evaluation of outcomes compared to goals.
We have to ask students to consider the following:
<span>Did they accomplish what they planned to do?Were they distracted and how did they get back to work?Did they plan enough time or did they need more time than they thought?<span>Under what conditions did they accomplish the most work.
Hope this helps!!!!!
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