Arock of mass m is thrown horizontally off a building from a height h. the speed of the rock as it leaves the thrower's hand at the edge of the building is v0, as shown. m h v0 m what is the kinetic energy of the rock just before it hits the ground? 1. kf = 1 2 m v2 0 2. kf = 1 2 m v2 0 − m g h 3. kf = 1 2 m v2 0 + m g h 4. kf = m g h − 1 2 m v2 0 5. kf = m g h

A rock of mass m is thrown horizontally off a building from a height h

As, the total energy of rock at the time of leaving the thrower's hand is the sum of gravitational potential energy and the initial kinetic energy.

As, the height from the ground decreases, the potential energy before hitting the ground is zero and the total final energy is just kinetic energy:

As, the law of conservation of energy states the total final energy must be equal to the initial energy.

Hence, the final kinetic energy will be

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a small object of mass 3.66 g and charge -17.6 µc is suspended motionless above the ground when immersed in a uniform electric field perpendicular to the ground. what are the magnitude and direction of the electric field?

at positions a, g kinetic energy is maximum.

at position d, potential energy is maximum.