An 80-kg man is one fourth of the way up a 10-m ladder that is resting against a smooth, frictionless wall. If the ladder has a mass of 30 kg and it makes an angle of 60° with the ground, find the force of friction of the ground on the foot of the ladder
a. 7.8 × 10^2 N
c. 50 N
b. 2.0 × 10^2 N
d. 1.7 × 10^2 N
B
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Banked Curves: Two cars go around a banked curve at the proper speed for the banking angle. One car has tires with excellent traction, while the other car has bald slippery tires. Which of these cars is more likely to slide on the pavement as it goes around the curve?
A. the car with the new tires B. the car with the bald tires C. Neither car will slide. D. It depends on if the pavement is wet or dry.
Which of the following statements about neutrinos is true?
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The atmospheric pressure on Venus
A) shows an extreme change with the seasons. B) is much lower than on Earth. C) is about the same as on Mercury. D) is much higher than on Earth. E) causes variations in surface temperature.
Hubble's law implies that, at some time in the past, all the matter in the universe was at one place
Indicate whether the statement is true or false