When a spinning ice skater pulls in his arms, he spins faster because
A) his angular momentum must be conserved, so reducing his radius must increase his speed of rotation.
B) there is less friction with the air.
C) there is less friction with the ice.
D) there exists an unbalanced reaction force.
A) his angular momentum must be conserved, so reducing his radius must increase his speed of rotation.
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A 200-N block, on a 30° incline, is being held motionless by friction. The coefficient of static friction between the block and the plane is 0.60 . The force due to friction is:
a. 104 N. c. 60 N. b. 100 N. d. 0 N.
Using a camera with a fixed focal length lens, how will decreasing the f-number affect the depth of field and the intensity of the light reaching the ccd (or film)?
a. The depth of field will increase as will the intensity of light reaching the ccd. b. The depth of field will increase but the intensity of light reaching the ccd will decrease. c. The depth of field will decrease as will the intensity of light reaching the ccd. d. The depth of field will decrease but the intensity of light reaching the ccd will increase.
The brightest object in the sky is
a. the Sun. b. the Moon. c. Venus. d. Mars.
A supercluster refers to a large group of stars within the Milky Way
Indicate whether the statement is true or false