Of the planetary systems that may exist in our galaxy, what fraction may contain a habitable planet?
A) almost all
B) about half
C) about a tenth
D) only 1 in 50
E) less than 1 in 100
C
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From the edge of a roof top you toss a green ball upwards with initial velocity v0 and a blue ball downwards with the same initial velocity. When they reach the ground below,
A) the green ball will be moving faster than the blue ball. B) the blue ball will be moving faster than the green ball. C) the two balls will have the same speed.
An athlete doing push-ups performs 650 kJ of work and loses 425 kJ of heat. What is the change in the internal (thermal) energy of the athlete?
A) -225 kJ B) -1075 kJ C) 1075 kJ D) 225 kJ E) 276 kJ
A pure substance A having density of 800 kg/m^3 (56 lbm/ft^3) is diffusing into a binary mixture of A and B. If the velocity of A is 4 cm/hr (1.2 in/hr) into the mixture and the velocity of B is 3.6 cm/hr out of the mixture, what is the total bulk velocity? Assume that the density of pure B is 900 kg/m3 (63 lbm/ft^3) and that the mixture density is 890 kg/m^3 (61 lbm/ft^3).
What will be an ideal response?
The focal length of the lens of a simple camera is 40.0 mm. How far must the lens be moved to change the focus of the camera from a person 25 m away to one that is 4.0 m away?
A) 0.2 mm B) 0.3 mm C) 0.4 mm D) 0.5 mm E) 0.7 mm