In which situation is no work considered to be done by a force?
oa when the angle between the force and displacement is 180°
o b. when the angle between the force and displacement is 90°
oc when the angle between the force and displacement is 45°
od. when the angle between the force and displacement is 0°

Identify two factors that determine the rate of stream erosion

An implanted pacemaker supplies the heart with 72 pulses per minute, each pulse providing 6.0 v for 0.65 ms. the resistance of the heart muscle between the pacemaker’s electrodes is 550 ω. find (a) the current that flows during a pulse, (b) the energy delivered in one pulse, and (c) the average power supplied by the pacemaker.

Alead ball is dropped into a lake from a diving board 5m above the water . it hits the water with a certain velocity and then sink with constant velocity in bottom . it reaches the bottom 5 second after it is dropped if g= 10m/s2 . find depth of the lake and average velocity of the ball ?