Answer:
adapted from NOVA, a team of historians, engineers, and trade experts recreate a medieval throwing machine called a trebuchet. To launch a projectile, a trebuchet utilizes the transfer of gravitational potential energy into kinetic energy. A massive counterweight at one end of a lever falls because of gravity, causing the other end of the lever to rise and release a projectile from a sling. As part of their design process, the engineers use models to help evaluate how well their designs will work.
Explanation:
Answer:
take daily showers . eat vegies .sanitize your hands
Answer:the summery is ...i really don't know the picture is blurry and I cant see can you make it clear?
Explanation:
Answer:

Explanation:
When the block is displaced by x units
F= spring force
two springs are connected parallel

Writing Newtons second law, F = ma


a= x" ( differentiating x w.r.t time twice)

this the standard form of equation of oscillation spring mass system
This is the differential equation, x'' means that double differentiation of x , i.e, x'' is acceleration
since, Period 
therefore,

Answer:
C. 12m
Explanation:

from the graph v = 4m/s and t = 3 s
d = vt = 4 × 3 = 12 m