Atennis ball is hit straight up at 20 m/s from the edge of a sheer cliff. some time later, the ball passes the original height from which it was hit. (ignore the effects of air resistance.) (a) how fast is the ball moving at that time? m/s (b) if the cliff is 50 m high, how long will it take the ball to reach the ground level? s (c) what total distance did the ball travel? m

Why is there friction between objects

For problems 1-3, consider a simple dc brush motor with a permanent magnet stator. with an an consider a simple dc brush motor with a permanent magnet ae supply voltage of 100 v, the no-load speed of the motor is 1000 rpm. this motor can provide a torque of 1.9 n-m at 800 rpm drawing a current of 2 a current are both zero at no load.) 1. with an armature supply voltage of 100 v, the motor is operated at 900 rpm. what is the motor torque? what is the mechanical power delivered by the motor? what is the current draw? what is the electrical power input? what is the energy efficiency of the motor? with an armature supply voltage of 100 v, the motor is operated at 1100 rpm (where it acts as a generator). what torque input is required? what mechanical power is required what current is generated? what is the electrical power generated? what is the energy efficiency of the motor acting as a generator? 2. with an armature supply voltage raised to 120 v, the motor is operated at 1000 rpm. what is the no-load speed? what is the motor torque? what is the mechanical power delivered by the motor? what is the current draw? what is the electrical power input what is the energy efficiency of the motor? 3.

For waves in the ocean, the medium of the waves is a. air b. water c. energy d. a passing boat