Amerry-go-round modeled as a disk of mass m 7.00 x 10 kg and radius r vertical axle (see figure). 2.40 m is rotating in a horizontal plane about a frictionless (a) after a student with mass m =90.0 kg jumps onto the merry-go-round, the system's angular speed decreases to 1.95 rad/s. if the student walks slowly from the edge toward the center, find the angular speed of the system when she reaches a point 0.450 m from the center rad/s (b) find the change in the system's rotational kinetic energy caused by her movement to the center t (c) find the work done on the student as she walks to r 0.450 m. exercise getting started i'm stuck! hints: use the values from the practice it section to answer this exercise. (a) find the angular speed of the merry-go-round before the student jumped on, assuming the student didn't transfer any momentum or energy as she jumped on the merry-go-round. rad/s (b) by how much did the kinetic energy of the system change when the student jumped on? notice that energy is lost in this process, as should be expected, since it is essentially a perfectly inelastic collision. ke,- ke,= need ?

Aroll in a paper machine is powered by a separately excited dc machine. operating point 1 (under load): the roll typically operates at 764 rpm and must provide 301 nm of torque to oppose the load of the paper. the armature voltage is 230v for this operating point operating point 2 (no load): when the load is removed the speed of the roll increases to 900 rpm (the field characteristics are unchanged) la ea dev m (a) calculate the maximum torque (units of nm) that the motor can supply with this applied voltage (b) calculate the value of the armature resistance, ra (in ohms) (c) at operating point 1 (loaded condition), the field current, i, and the total input power (armature field), are measured to be to be 10 a and 28,600 w respectively. use this information to calculate the value of the field resistance, rf (in ohms). (d) (d) at operating point 1 (loaded condition), calculate the motor efficiency. express your answer as a percent to at least 2 significant digits. (d) if the field voltage is reduced by 1/2, calculate the new stall torque (in nm) of the motor (f). if the field voltage is reduced by 1/2, calculate the new no-load speed (in rad/sec)

The place you get your hair cut has two nearly parallel mirrors 6.00 m apart. as you sit in the chair, your head is 2.00 m from the nearer mirror. looking toward this mirror, you first see your face and then, farther away, the back of your head. (the mirrors need to be slightly nonparallel for you to be able to see the back of your head, but you can treat them as parallel in this problem.) how far away does the back of your head appear to be?

How many hydrogen (h) atoms are in one molecule of sulfuric acid, h2so4? (1 points) 1 2 4 7