A 1.2-kg mass is projected up a rough circular track (radius = 0.80 m) as shown. The speed of the mass at point A is 8.4 m/s, and at point B, it is 5.6 m/s. What is the change in mechanical energy between A and B caused by the force of friction?
a.
?2.7 J
b.
?8.8 J
c.
?4.7 J
d.
?6.7 J
e.
?19 J
c
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A 5.00-g lead BB moving at 44.0 m/s penetrates a wood block and comes to rest inside the block. If half of its kinetic energy is absorbed by the BB, what is the change in the temperature of the BB? The specific heat of lead is 128 J/kg ? K
A) 0.940 K B) 1.10 K C) 1.26 K D) 2.78 K E) 3.78 K
Molecules like water in which electrons are distributed unevenly within the molecule are referred to as
A) bipolar B) ionic C) charged D) polar
Very importantly, a hydraulic press can multiply
A) forces. B) pressures. C) energy. D) all of the above E) none of the above
A bullet moving horizontally with a speed of 500 m/s strikes a sandbag and penetrates a distance of 10 cm
(a) What is the average acceleration of the bullet? (b) How long does it take to come to rest?