1) A stone is thrown from the top of a building at an angle of 25* upward with r
ID: 1780079 • Letter: 1
Question
1) A stone is thrown from the top of a building at an angle of 25* upward with respect to the horizontal and with an initial speed of 15 m/s. If the stone is in flight for 3.0 s, how tall is the building? How far from the base of the building does the stone hit the ground? A crate is traveling down a 33* incline. If the coefficient of kinetic friction between the crate and ramp is 0.22, what is the crate's acceleration? 2) Two of you are trying to break a cord. Your friend suggests that you each pull on opposite ends in opposite directions and you suggest that you tie the cord to a pole and each pull together from the end opposite the pole. Which plan is more likely to work and why? Show Free-Body diagrams of each case. 3) Two horses are pulling a 1200 kg carriage down the road at a constant speed against a frictional force of 464 N. Assuming the horses share the load equally, how much work does each horse do on the carriage to move it 53 m? What is the net work done on the carriage by all sources? 4) A mass, m, is launched along and up a frictionless ramp using a spring launcher with a spring constant, k. In order for the mass to achieve a maximum height of h, how far must the spring be compressed? How fast is the block moving at ¾ of this height? 5) 7 PHYS 1180 College Physics- Fall 2017 McCExplanation / Answer
1)
consider the motion along the Y-direction :
Voy = initial velocity = 15 Sin25 = 6.34 m/s
Y = ?
t = time = 3 sec
a = acceleration = - 9.8
using the equation
Y = Voy t + (0.5) a t2
Y = 6.34 (3) + (0.5) (- 9.8) (3)2
Y = - 25.08
so height = 25.08 m
along the horizontal direction
X = horizontal distance travelled
Vox = initial velocity = 15 Cos25 = 13.6 m/s
t = time = 3 sec
using the equation
X = Vox t
X = 13.6 x 3 = 40.8 m
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