Phys101
Term: 123
Online HW-Ch02-Lec02
Q1:
An object moves along the x-axis, its position measured at each instant of
time. The data are organized into an accurate graph of x vs. t. Which of the
following quantities cannot be obtained from this graph?
A. The velocity at any instant
B. The acceleration at any instant
C. The displacement during some time interval
D. The average velocity during some time interval
E. The speed of the particle at any instant
Ans:
B
Q2:
A ball is thrown directly downward with an initial speed of 8.00 m/s, from a height of
30.0 m. After what time interval does it strike the ground?
Ans:
vy 2 = v0y 2 + 2ay (∆y) ⇒ vy = �v0y 2 + 2𝑎𝑦 ∆y = �82 + 2(−9.8)(−30)
vy = −25.5 m/s
vy = v0y − gt ⇒ t =
vy − v0y
−25.5 − (−8)
=
= 1.79 s
−g
−9.8
Q3:
A truck covers 40.0 m in 8.50 s while uniformly slowing down to a final velocity of
2.80 m/s. Find its acceleration?
Ans:
1
X − Xf = vf t − at 2 (table 2 − 1 , page 23)
2
1
40 = (2.8)(8.5) − a (8.5)2
2
⇒ a = −0.448 m/s2
KFUPM-Physics Department
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