A 2.0-kg mass swings at the end of a light string (length = 3.0 m). Its speed at the
1 answer:
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<h2>a) Average velocity in first 4 seconds is 64 ft/s upward</h2><h2>b) Average velocity in second 4 seconds is 63.5 ft/s downward</h2>
Explanation:
a) Given S(t) = 76 + 128t − 16t²
s(0) = 76 + 128 x 0 − 16 x 0² = 76 ft
s(4) = 76 + 128 x 4 − 16 x 4² = 332 ft
Displacement in 4 seconds = 332 - 76 = 256 ft
Time = 4 - 0 = 4 s
Average velocity in first 4 seconds is 64 ft/s upward
a) Given S(t) = 76 + 128t − 16t²
s(4) = 76 + 128 x 4 − 16 x 4² = 332 ft
s(8) = 76 + 128 x 8 − 16 x 8² = 78 ft
Displacement in 4 seconds = 78 - 332 = -254 ft
Time = 4 - 0 = 4 s
Average velocity in second 4 seconds is 63.5 ft/s downward
Answer:
, downward
Explanation:
There is only one force acting on the ball during its motion: the force of gravity, which is given by
where
m is the mass of the ball
is the acceleration of gravity (downward)
According to Newton's second law,
where F is the net force on the object and a is its acceleration. Rearranging for a,
As we said, the only force acting on the ball is gravity, so F = mg and the acceleration of the ball is:
Therefore, the ball has a constant acceleration of downward for the entire motion.