Download Newton`s 2nd Law

Physics 10
Newton’s 2nd Law
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A rocket becomes progressively easier to
accelerate as it travels through space.
Why is this so? (Hint: About 90% of the
mass of a newly launched rocket is fuel.)
⇒ From Newton’s 2nd law, a = Fnet/m.
As fuel is burned, the mass of the
rocket becomes less. As the mass
decreases, the acceleration increases.
On a long alley, a bowling ball slows
down as it rolls. Is any horizontal force
acting on the ball? How do you know?
⇒ Yes, if the ball slows down, then a
(net) force must be causing the
acceleration. The force is probably air
resistance and friction between the ball
and alley.
A common saying goes, “It’s not the fall that
hurts you; it’s the sudden stop.” Translate
this into Newton’s laws of motion.
⇒ When you stop suddenly, your velocity
changes rapidly, which means a large
acceleration. By Newton’s second law, this
means the force that acts on you is also large.
Experiencing a large force is what hurts you.
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