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The actual mechanical advantage of a pulley is 2. The pulley has 3 supporting strings. What is the efficiency of the pulley?
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KGUS eNotes educator | CERTIFIED EDUCATOR
Hello.
The efficiency of a simple machine can be expressed as the ratio of the actual mechanical advantage divided by the theoretical mechanical advantage. You were given the actual mechanical advantage as 2, so you only need to determine the theoretical mechanical advantage. With a pulley system, this becomes a simple matter of determining how many strings support the pulley, which was nicely given as three. Therefore, the efficiency in this case is 2/3, or about 67%.
Answer:Let’s assume that, after the soccer ball is kicked and moves through its trajectory, it first makes contact with level ground a horizontal distance of 35 meters from where it was kicked. Let’s also assume that we can neglect air resistance. The time, t, that the soccer ball is in the air until it first contacts the ground can be found from the equation h = (1/2)gt^2 which can be rewritten as t = sqrt(2h/g) where h is the vertical distance the ball falls which is the height of the hill since the ball was kicked horizontally, and g is the acceleration of gravity which is 9.8 m/s^2. So t = sqrt(2(22)/9.8) = 2.12 seconds. In that time, the ball travelled 35 meters so its horizontal velocity was 35 meters/2.12 seconds = 16.5 meters/second.
Explanation:
Answer:
D,E,F
Explanation:
d. Earth's geographic north pole is actually a magnetic south pole.
e. The south poles of two bar magnets will repel each other.
f. The north pole of a bar magnet will attract the south pole of another bar magnet.
In a magnetic field like poles repel and unlike poles attract each other. The like poles which is south to south or north to north repel each other and the unlike poles which is north to south or south to north attract each other which makes E and F correct.
A is correct because compasses points to the North Pole when places in the Southern Hemisphere.
The size doesn't matter, the density is always the same. It's 2.07