If the object is moving in a straight line with constant speed,
that's a description of " acceleration = zero ".
Zero acceleration means zero net force on the object.
NO net force is 'required' to keep an object moving in a straight line
at constant speed. In fact, if there IS any net force on the object,
then either its speed or its direction MUST change ... there's no way
to avoid it.
None of this depends on the object's mass, or on the speed or direction
of its motion.
Answer:
The kinetic energy of the bullet is 5.4 × 10³ J
Explanation:
Hi there!
The equation of kinetic energy is the following:
KE = 1/2 · m · v²
Where:
KE = kinetic energy.
m = mass of the bullet.
v = speed of the bullet.
Let´s convert the mass unit to kg so that our result is in Joules:
64 g · ( 1 kg / 1000 g) = 0.064 kg
Then, the kinetic energy will be the following:
KE = 1/2 · 0.064 kg · (411 m/s)²
KE = 5.4 × 10³ J
You said that she's losing 1.9 m/s of her speed every second.
So it'll take
(6 m/s) / (1.9 m/s²) = 3.158 seconds (rounded)
to lose all of her initial speed, and stop.
