Hey Guys! Please help me solving this 3 problems 21. An object starts from rest
ID: 1642295 • Letter: H
Question
Hey Guys! Please help me solving this 3 problems
21.An object starts from rest at time t = 0.00 s and moves in the +x direction with constant acceleration. The object travels 3.00 m from time t = 1.00 s to time t = 2.00 s. What is the acceleration of the object?
22.A car starts from rest and accelerates with a constant acceleration of 1.00 m/s2 for 3.00 s. The car continues for 5.00 s at constant velocity. How far has the car traveled from its starting point?
23.A ball rolls across a floor with an acceleration of 0.100 m/s2 in a direction opposite to its velocity. The ball has a velocity of 4.00 m/s after rolling a distance 6.00 m across the floor. What was the initial speed of the ball?
Plase help me, I need process, step by step, thanks!!
Explanation / Answer
21.
velocity of object at end of time 1s is
v=vi+at=0+a(1)=a .................(1)
diatance travelled by object fromt=1s to t=2s is given by
d=v(1)+(1/2)a(1)2=v+(1/2)a ..............(2)
from (1) and (2)
d=a+(1/2)a=(3/2)a
so a=(2/3)d=(2/3)(3)=2 m/s2
so acceleration of the object=2 m/s2
22.
distance travelled by car during acceleration period is given by
d1=(1/2)at2=(1/2)(1)(3)2=4.5 m
velocity at the end of acceleration period isgiven by
v=at=(1)(3)=3 m/s
distance travelled by car during constant velocity period
d2=vt=(3)(5)=15 m
Total distance travelled by car=d1+d2=4.5+15=19.5m
Total distance travelled by car=d1+d2=19.5m
23.
let initial velocity of ball is v
final veocity in constant accelerated motion is given by
vf2=v2+2ad
so 42=v2+2(-1.5)(6) a is negative because opposite to motion
so v=5.83 m/s
initial speed of the ball=5.83 m/s