A 2.0-kg block slides on a frictionless 25° inclined plane. A force of 4.6 N acting parallel to the incline and up the incline is applied to the block. What is the acceleration of the block?
a. 1.8 m/s2 up the incline
b. 2.3 m/s2 up the incline
c. 6.6 m/s2 down the incline
d. 1.8 m/s2 down the incline
e. 2.3 m/s2 down the incline
d
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A person throws three rocks off a cliff of height h at exactly the same speed 
, each time, but throwing rock A almost vertically upward, rock B horizontally, and rock C almost vertically downward (see the diagram below). 
Which rock hits the ground with the greatest speed? (Ignore air friction.) A. Rock A B. Rock B C. Rock C D. Rocks A and C hit with the same speed, faster than B. E. All three rocks hit with the same speed.
A car is going around a banked curve at a high rate of speed. For the car not to skid, in which direction does the frictional force act?
A. Up the plane. B. Down the plane. C. Directly towards the center of the curve.
Uncertainty Principle Using Momentum and Position: Suppose that the speed of an electron traveling 1.0 km/s is known to an accuracy of 1 part in 10,000 (that is, within 0.01%). What is the minimum uncertainty in the position of this electron? (melectron = 9.11 × 10-31 kg, h = 6.626 × 10-34 J ? s)
Fill in the blank(s) with the appropriate word(s).
Consider the same scenario as in the previous problem: Two twin sisters, Gwen and Jackie, are both 20 years old in the year 2020. Jackie takes off on a round-trip to Vega, 25 light-years away. She travels at an average speed of 0.9999c
Which of the following best describes the situation according to Jackie? A) She stays still, while Earth rushes away from her at 0.9999c and Vega rushes toward her at 0.9999c. Since Vega is 25 light-years away, she says it takes Vega about 25 years to reach her. B) She says that the 25 light-year trip takes only a few months, and therefore concludes that she is traveling faster than the speed of light. C) It takes her 25 years to reach Vega. D) She stays still, while Earth rushes away from her at 0.9999c and Vega rushes toward her at 0.9999c. She sees the distance from Earth to Vega shortened considerably from 25 light-years, and therefore it takes far less than 25 years for Vega to reach her.