Consider the car driving around a circular track .once stated, the driver maintains a speed 0f 45m/h. compare the driver's velocity with his acceleration in this case.
a.)the car is accelerating because it is changing direction but the velocity is constant.
b.)the car is traveling at a constant rate of speed so it is not accelerating and the velocity does not change
c.)acceleration is the change in velocity so the car is experiencing a change in velocity and it is accelerating
d.)the car is traveling at a constant rate of speed so it is not accelerating but the velocity changes because the direction the car travels is constantly changing.

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j