Answer: 24 N
Explanation:
Given that the
Mass m = 4 kg
Coefficient of friction (μ) = 0.60
To calculate the static friction between the block and the table before any attempted motion, you will use the formula; F = (μ)N
Where
F = static friction
N = normal reaction = mg
g = acceleration due to gravity = 9.8 m/^2
Substitutes m, g and (μ) into the formula
F = 0.6 × 4 × 9.8
F = 23.52 N
Therefore, the static friction between the block and the table before any attempted motion is 24 N approximately.
<span>(cp of Copper = 387J / kg times degrees C; cp of Aluminum = 899 J / kg times degrees C; cp of Water = 4186J / kg times degrees C)
</span> Use the law of conservation of energy and assuming no heat loss to the surroundings, then
<span>Heat given up by copper = heat absorbed by water + heat absorbed by calorimeter
</span><span> Working formula is
</span> <span>Q = heat = MCp(delta T)
</span><span> where
</span><span> M = mass of the substance
</span><span> Cp = specific heat of the substance
</span><span> delta T = change in temperature
</span> Heat given up by copper = 0.10(387)(95 - T)
<span> Heat absorbed by water = 0.20(4186)(T - 15)
</span><span> Heat absorbed by calorimeter = 0.28(899)(T - 15)
</span> where
<span> T = final temperature of the system
</span><span> Substituting appropriate values,
</span> 0.10(387)(95 - T) = 0.20(4186)(T - 15) + 0.28(899)(T - 15)
<span> 38.7(95 - T) = 1088.92(T - 15)
</span><span> 3676.50 - 38.7T = 1088.92T - 16333.8
</span><span>1127.62T = 20010.3
</span><span> T = 17.75 C </span>
Key concepts
Heart rate
Exercising
The heart
Cardiovascular system
Health
Introduction
As Valentine's Day approaches, we're increasingly confronted with "artistic" images of the heart. Real hearts hardly resemble to two-lobed shapes adorning cards and candy boxes this time of year. And the actual shape of the human heart is important for its function of supplying blood to the entire body. You have likely noticed that your heart beats more quickly when you exercise. But have you ever taken the time to observe how long it takes to return to its normal rate after you're done exercising? In this science activity you'll get to do some exercises to explore your own heart-rate recovery time.
Background
Your heart is continuously beating to keep blood circulating throughout your body. Its rate changes depending on your activity level; it is lower while you are asleep and at rest and higher while you exercise—to supply your muscles with enough freshly oxygenated blood to keep the functioning at a high level. Because your heart is also a muscle, exercise, in turn, helps keep it healthy. The American Heart Association recommends that a person does exercise that is vigorous enough to raise their heart rate to their target heart-rate zone—50 percent to 85 percent of their maximum heart rate, which is 220 beats per minute (bpm) minus their age for adults—for at least 30 minutes on most days, or about 150 minutes a week in total. So for a 20-year-old, the maximum heart rate would be 200 bpm, with a target heart-rate zone of 100 to 170 bpm. (For those 19 or younger, target zones can vary more than they do for adults.)
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Answer:
Total charge flow through the cooker is 21600 C
Explanation:
As we know that the current flow through the cooker is given by Ohm's law
here it is given as
now the charge flow through it is given as
total time is t = 8 hours
Answer: 580 N
Refer to attached figure.
The angle of inclination is 22 degrees
weight (gravitational force) acts downwards.
Normal force is a contact force which acts perpendicular to the point of contact.
The horizontal component (mg cos 22 ) balances the normal force and the vertical component balances the frictional force.
Gravitational force on an object = mg
The normal force 
