A 4 kg block with a 1 kg block stacked on top initially slides at 2 m/s on a rough, horizontal
surface. The blocks continue to move as a unit with no sliding between the two. The blocks come to rest 1 m
away.

15. How much work did kinetic friction from the surface below do on the 4 kg block during this process?
a) -2 J
b) -6 J
c) -10 J
d) -14 J
e) -18 J

16. How much work did static friction from the 1 kg block above do on the 4 kg block during this process?
a) +2 J
b) +6 J
c) +10 J
d) +14 J
e) +18 J

17. What is the coefficient of kinetic friction between the 4 kg block and the surface below?
a) 0.35
b) 0.30
c) 0.25
d) 0.20
e) 0.15

Expert

a charge 3q is at the origin, and a charge −2q is on the positive x axis at x=a. part a where on the x-axis would you place a third charge so it would experience no net electric force? enter an expression for the exact answer, which will involve a square-root sign. (do not enter an approximate decimal answer.)

i think it's 35 meters

prndulum needs thread, weight clock to time swings

the aurora is formed when charged particles emitted from the sun during a solar flare penetrate the earth's magnetic shield and collide with atoms and molecules in our atmosphere. these collisions result in countless little bursts of light, called photons, which make up the aurora.

auroras are generated by charged solar particles hitting molecules in earth's atmosphere. this usually happens in high latitudes, because our planet’s magnetic field tends to funnel these particles toward the poles. that’s why it can be experienced in northern ohio.