QTest #3-solutions - Version 082/ABBAC QTest#3...

Version 082/ABBAC – QTest #3 – Antoniewicz – (56445) 1
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001 10.0points
A target lies flat on the ground 10 m from
the side of a building that is 10 m tall, as
shown below.
The acceleration of gravity is 10 m / s
2
. Air
resistance is negligible.
A student rolls a 10 kg ball off the horizontal
roof of the building in the direction of the
target.
10 m
10 m
v
10 m
The horizontal speed v with which the ball
must leave the roof if it is to strike the target
is most nearly
1. v =
10
√
3
3
m/s.
2. v = 10
√
2 m/s.
3. v =
√
5
10
m/s.
4. v = 10
√
3 m/s.
5. v = 5
√
2 m/s. correct
6. v =
√
3
10
m/s.
7. v =
√
2
10
m/s.
8. v = 3
√
10 m/s.
9. v = 10
√
5 m/s.
10. v = 2
√
10 m/s.
Explanation:
m = 10 kg , not required
h = 10 m ,
x = 10 m , and
g = 10 m / s
2
.
Observe the motion in the vertical direction
only and it is a purely 1-dimension movement
with a constant acceleration. So the time
need for the ball to hit the ground is
t =