A block w/ a mass M=4.85 kg is resting on a slide that has a curved surface. There is no friction. the speed of the block after it has slid along the slide sufficiently far for it vertical drop to be 19.6 m is
a. 19.6 m/s
b. 73 m/s
c. 43.2 m/s
d. 384 m/s
e. problem cannot be solved
the average marathon runner can compete the 42.2 km distance of the marathon in 3 hours and 30 mins. If the runner's mass is 75 kg what is the runner's average kinetic energy during the run?
a. 25 J
b. 5450 J
c. 126J
d. 842 J
e. 421 J
A boy is standing at the stern (back) of a boat that is 8.0 m long. there is no friction btw the boat and water. the boy's mass is 63 kg and the boat's mass is 780 kg. the front of the boat is touching a dock and the force and aft axis of the boat is perpendicular to the dock. the boy walks from the stern of the boat to the bow. when he reaches the bow his distance from the dock is?
a. 0.51 m
b. 0.56m
c. 1.3m
d. 0.65m
e. 7.6m
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1 response so far ↓
1 Hyphy99 // Jun 30, 2008
I dont understand what you want for #1 and for 3 you need to draw a picture
for two you need to find his speed
so 42.2km/3.5 hours = 12.0571 kph * 1000 = 12,057.1 meters per hour / 60 = 200.952 meters per minute / 60 = 3.34921 m/sec
he weighs 75 kg so KE = (1/2)mv^2
plug in the numbers
(.5)(75)(3.34921)^2 = 420.644 J
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