1.
Vector
A
= 2
i
– 3
j
and vector
B
= 4
i
+ 6
j
. Find
A
⋅
B
and the angle
between the two vectors.
2.
A force
F
= 3 N
i
– 5 N
j
produces a displacement on a particle given
by
s
= 5 m
i
– 2 m
j
. Find the work done by the force.
3.
What is the work done to raise a 50kg box to a height of 3.0 m?
4.
A tractor exerts a constant force of 4.5
×
10
4
N in moving a load
horizontally a distance of
150 m. (i) What is the work done? (ii) If the
tractor does this work in 45 s, what is the power developed by its
engine?
5.
A hot air balloon with a mass of 50 kg ascends at a constant rate of
1.8 ms
1
for 1.2 minutes. What is the work done by the upward
buoyant force?
6.
A force F
x
= 15x
3
acts on a particle. Find the work done by the force
when the particle is displaced from x = 2.2 m to x = 3.5 m
7.
Find the work done to pull a 50kg crate uniformly 3.5 m up an
inclined plane of inclination 37
o
if the coefficient of kinetic friction
between the crate and the plane is 0.52.
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 Fall '10
 George
 Physics, Force, Work

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