Why is a device never 100% efficient? * a) Mechanical Advantage

b) Work

c) Friction

d) Speed Ratio

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for science lovers!!

Asmall grinding wheel has a moment of inertia of 4.0×10−5 kg⋅m2 . what net torque must be applied to the wheel for its angular acceleration to be 150 rad/s2 ?

Geologists get to play with chemistry, physics, and history! and what a history you will meet as youwork your way through the course. starting at the beginning, the textbook provides the scientifically acceptedstart of the and promises that you'll get to explore some of the evidence for that scientific view, later inthe semester. meanwhile, which is more nearly correct of the scientifically accepted view? a) the earth formed when the big bang caused older materials to fall together, about 14 billion years ago. b) the earth formed from the falling together of older materials, about 4.6 billion years ago. c) the earth formed in the big bang, about 6000 years ago. d) the earth is eternal, having been here forever and promising to be here forever. e) the earth was assembled by gigantic space beavers, which gnawed down the primordial tree of life andpiled its branches together to form the planet.

The cheetah is considered the fastest running animal in the world. cheetahs can accelerate to a speed of 20.1 m/s in 2.50 s and can continue to accelerate to reach a top speed of 28.1 m/s. assume the acceleration is constant until the top speed is reached and is zero thereafter.1) starting from a crouched position, how long does it take a cheetah to reach its top speed? (express your answer to three significant figures.) s2) how far does it travel in that time? (express your answer to three significant figures.) m3) if a cheetah sees a rabbit 120 m away, how long will it take to reach the rabbit, assuming the rabbit does not move? (express your answer to three significant figures.)