Physics 151 – Kinematics Problem Solving Example-KEY
Problem: On October 9, 1992, a 27-pound meteorite struck a car in
Peekskill, NY, leaving a dent 22 cm deep in the trunk. If the meteorite struck
the car with a speed of 550 m/s, what was the magnitude of its deceleration,
assuming it to be constant?
Draw a simple diagram
showing the meteor’s starting
and ending points and the
origin and direction of increase of your
coordinate system.
Write out the values of the known and solve variables.
Known: Solve:
v0 = 550 m/s a = ?
v = 0 m/s
x = 0.22 m
What is the variable “Not Involved”? t
Which kinematic equation does that suggest that you should use? 22
02vv ax=+
Solve that kinematic equation for the variable of interest?
Plug in the known values and solve for the desired quantity?
And since we are asked for magnitude, the minus sign is not needed.
Are the units on your answer correct? YES Correct number of sigfigs? YES – 2!
Does your answer appear reasonable? Hard to say -- we should certainly expect a large
value of acceleration since the meteor is brought to a stop very quickly.
22
0
22
0
22
0
2
2
2
vv ax
vv ax
vv a
x
=+
−=
−=
()
2
2
22 5
02
0550
6.9 10
220.22
mm
vv m
ss
a
x
ms
⎛⎞⎛ ⎞
−
⎜⎟⎜ ⎟
−⎝⎠⎝ ⎠
== =−×
Original top
of car trun
k
Final top
of car trunk
meteor
v = 0 m/s
v0 = 550 m/s
x = 0.22 m
X
