Test 1A WITH KEY

Question15whatarethemagnitudeanddirectionofthet

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Unformatted text preview: eleration due to gr avity is 3.7 m/s2. How far would a rock fall in 5 seconds if you dropped it on Mars? (Ignore the friction o f the thin Martian atmosphere.) a. b. c. d. must know the rock’s mass 19 m 46 m 93 m PHYS115 ‐ Spring 2013 6 Test 1 ‐ 4 March 2013 line of initial angular action speed = ? rotational mass I = 4 kg∙m2 P radiius string 1 m Questions 15 and 16 both refer to the ad‐ constant force jacent figure of a spinning disk. The initial 48 N angular speed is unknown. P and Q indicate directions along the dotted arrows. Question 15 – What are the magnitude and direction of the t orque vector? a. b. c. d. 48 N∙m, direction Q 12 N∙m, direction P 12 N∙m, direction Q 96 N∙m, direction Q After 2 seconds, the disk temporarily stops spinning. Question 16 – What were the magnitude and direction of the initial angular velocity? a. 96 rad/s, direction P b. 24 rad/s, direction P c. 48 rad/s, direction Q d. 48 rad/s, direction P Q PHYS115 ‐ Spring 2013 7 Test 1 ‐ 4 March 2013 Question 17 – Why does an archer aim somewhat above her target? Why can’t she simply aim directly at the bull’s‐eye to hit it? a. b. c. d. otherwise she cannot see her target the arrow will fall in flight, so she must compensate for its loss of height to increase the acceleration of the arrow because leaning back gives a (small) ramp force to make the arrow hit the target with more speed Question 18 – Which of a car’s devices can be used to cause a car to accelerate? ( = yes, = no) steering wheel brake pedal gas pedal a. b. c. d. Question 19 – One type of home coffee grinder has a small blade that rotates very rapidly and cuts the coffee beans into powder. Nothing prevents the coffee beans from moving. Why don’t the beans get out of the way when the blade begins to push on them? a. b. c. d. gravity holds them in place they have ine...
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