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Question
Physics
The velocity of an 800 g object changes from v0 =(3i-4j)ms-1 to vf =(6j+2K)ms-1change in kinetic energy is
Q. The velocity of an 800 g object changes from
v
0
=
(
3
i
−
4
j
)
m
s
−
1
t
o
v
f
=
(
6
j
+
2
K
)
m
s
−
1
change in kinetic energy is
6275
242
KEAM
KEAM 2004
Work, Energy and Power
Report Error
A
3 J
13%
B
6 J
50%
C
2 J
22%
D
1.5 J
16%
Solution:
Given m = 800 g = 0.8 kg
v
0
=
(
3
i
−
4
j
)
m
s
−
1
v
0
=
v
0
v
0
=
(
3
i
−
4
j
)
.
(
3
i
−
4
j
)
= 9+16 = 25
v
f
=
(
−
6
j
+
2
k
)
m
s
−
1
v
f
2
=
v
f
.
v
f
=
(
−
6
j
+
2
k
)
(
−
6
j
+
2
k
)
=
36
+
4
=
40
Change in KE =
2
1
m
(
v
f
2
−
v
0
2
)
2
1
×
0.8
(
40
−
25
)
=
6
J