If the velocity versus time graph of an object is a horizontal line, the object
ID: 1655565 • Letter: I
Question
If the velocity versus time graph of an object is a horizontal line, the object is A) moving with constant speed. B) moving with constant non-zero acceleration. C) at rest. D) moving with infinite speed. E) none of the above 8) A car is moving with a constant acceleration. at t = 5.0 s its velocity is 8.0 n/s abd at t = 8.0 s its velocity 12.0 m/s. What is the distance travelled in that interval of time? A) 6 m B) 10 m C) 30 m D) 40 m E) 40 m F) 50 m G) 470 m 9) A heavy rock is dropped from rest at the top of a cliff and falls 100 m before hitting the ground. How does the rock take to fall to the ground and what is the magnitude of the velocity just before it hits? A. 4.5 s, 0 m/sExplanation / Answer
at t=5
velocity v5 = vo + a*t
v5 = vo + 5*a
8 = v0 + 5*a .........(1)
at t = 8 s
velocity
v8 = v0 + a*t
v8 = v0 + 8a
12 = v0 + 8a ..............(2)
from 1 & 2
12 - 8 = 8a - 5a
4 = 3a
a = 4/3 m/s^2
v8^2 - v5^2 = 2*a*s
12^2 - 8^2 = 2*(4/3)*s
distance travelled s = 30 m <<<<<<-------------ANSWER
OPTION D