A ball is thrown vertically upwards at 14.7 m/s. For its complete trip up and ba

Question

A ball is thrown vertically upwards at 14.7 m/s. For its complete trip up and back to the starting position), its average speed is: a. 11.03 m/s b. 7.35 m/s c. 14.7 m/s d. 3.68 m/s e. not given. A rock is thrown straight down with an initial an initial velocity of 14.9 m/s from a cliff. What is the rock's displacement after 1.0 s? a. 25. m b. 20 m c. 35 m d. 6 m e. 15 m *A rock is thrown from the edge of the top of a 100-ft tall building at some unknown angle above the horizontal. The rock strikes the ground a horizontal distance of 160 ft from the base of the building 5.0 s after being thrown. Assume that the ground is level and that the side of the building is vertical. Determine the speed with which the rock was thrown. a. 72 ft/s b. 77 ft/s c. 68 ft/s d. 82 ft/s e. 87 ft/s A plane is moving due north, directly towards its destination. Its airspeed is 200 mph. A constant breeze is blowing from west to east at 40 mph. How long will it take for the plane to travel 200 miles north? a. one hour b. more than one hour c. less than one hour d. more information is needed If we know that a nonzero net force is acting on an object, which of the following must we assume regarding the object's condition? The object is: a. at rest b. moving with a constant velocity c. being accelerated d. levitating in the same position.

Explanation / Answer

6) v = 14.7 m/s

average speed = (14.7+14.7)/2 = 14.7 m/s

correct option is (c)

7) u = 14.9 m/s, t = 1 s

s = ut +0.5at^2

s = 14.9*1 +0.5*9.8*1^2 = 20 m

correct option is (b)

8)s = 100 ft, R = 160 ft, t = 5 s

R = ucos(theta)*t

160 = ucos(theta)*5

ucos(theta) = 32 ft/s

s = (usin(theta)^2/2g

100 = (usin(theta)^2/(2*32.15)

usin(theta)= 80.2 ft/s

u = (32^2 +80.2^2)^0.5

u = 87 ft/s

correct option is (c)

9) d = 200 miles

vp = 200 j mph , vw = 40 i mph

velocity = d/t

t = 200/200 = 1 hour

correct option is (a)

10) correct opiton is (c)

From Newton second law F = ma

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