A
79 at time t=0, a rock
climber accidentally allows a
piton to fall freely from a high
point on the rock wall to the val-
ley below him. then, after a
short delay, his climbing partner,
who is 10 m higher on the wall,
throws a piton downward. the
positions y of the pitons versus t
during the falling are given in
fig. 2-40. with what speed is the
second piton thrown?
0
3
1 2
t(s)
fig. 2-40 problem 79.

Which object is most likely represented by a dot?

Two conductors, a and b, are each in the shape of a tetrahedron. but of different sizes. they are charged in the following manner: 1. tetrahedron a is charged from an electrostatic generator to charge q. 2. tetrahedron a is briefly touched to tetrahedron b. 3. steps 1 and 2 are repeated until the charge on tetrahedron b reaches a maximum value. if the charge on tetrahedron b was q/4 after the first time it touched tetrahedron a. what is the final charge qbmax on tetrahedron b?

Asmall grinding wheel has a moment of inertia of 4.0×10−5 kg⋅m2 . what net torque must be applied to the wheel for its angular acceleration to be 150 rad/s2 ?