The coefficient of kinetic friction for a 21 −kg bobsled on a track is 0.10.   What force is required to push it down a 5.0 ∘∘ incline and achieve a speed of 60 km/h at the end of 75 mm? Express your answer using two significant figures.

السؤال 34 One of the following could be a kinetic friction coefficient Hk: 0.15 N O 0.15J O 0.15 O 0.15 N/m Up O

ved 161 A single cable is wrapped from the center of pulley A, around pulley B, and around pulley A. This cable is pulled downward at 2 m/s. At what speed does pulley B move upward? V = 1 S L= take a time derivitive 0-2 VAB+ VAC dB C WEIGHT 2 m/s de

a) Given the following ideal Atwood machine in an elevator accelerating down at ae = 4.9 m/s2, with m1 = 10 gram (two nickels) and m2 = 5 gram (one nickel) as shown, what is the tension T in the string in millinewton (mN)? (Hint: the upward arrow on ae is correct and just means use "positive is up" conventions for the elevator itself, so here we have ae = -4.9 m/s2 to be put into Einstein's rule that we discussed.) b) Exact same Atwood machine as the previous problem (two nickels and a nickel in an elevator accelerating down at 4.9 m/s2), but now how much time (s) does it take m1, starting from rest, to fall 25 cm relative to the inside of the elevator? I labeled it a and b because they are connected to each other. Please help, thanks!