Question
9) A child slides down a slide at daycare. She is released from rest at the top of the slide, and then slides down the practically frictionless slide for 2.1 s. If the slide is at an angle of 60 degrees above the horizontal, how fast is the child moving at the bottom of the slide? a. O m/s b. 9.8 m/s c. 17.8 m/s d. 10.29 m/s e. 8.49 m/s 10) A canon in a trench fires a ball from ground level with an initial velocity vo- 10-r + 12 . What is the total speed of the ball when it hits the ground? a. 22 m/s b. 12 m/s c. 15.6 m/s d. 244 m/s 11) The velocity of an object at any point in time is given by the vector: v(t) =-10t (s) 2.52(3 +1 the net force on the object in the j direction at t=10 seconds? t2 ) k . If the object is initially at rest, and has a mass of 0.20 kg, what is a. 5 N b. 1 N C. 50N d. 10 N
Explanation / Answer
9)
acceleration acting along the slide = g*sin thetha
= 9.8*sin 60
= 8.49 m/s^2
use:
vf = vi + a*t
= 0 + 8.49*2.1
= 17.8 m/s
Answer: c
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