Apendulum has a mass of 1.5 kg and starts at a height of 0.4 m. if it is
released from rest, how fast is it going when it reaches the lowest point of its
path? acceleration due to gravity is g = 9.8 m/s2

2.8 m/s

Explanation:

Energy of a system cannot be destroyed . It can only be transfer to another form of energy.

when the pendulum is at rest in a height 0.4 m ,  it has a potential energy due to the height it is. but no kinetic energy since ni movement (velocity)

at the time it reach the lowest point of the path , we can say that it is in the minimum potential level , therefore it now does not have any potential energy , but has a kinetic energy  

energy at rest = energy at lowest point

KE1 + PE1 = KE2 + PE2

0 + 1.5 * 9.8 *0.4=

V=√(2*9.8*0.4)

V = 2.8 m/s

close lines strong magnet less close weaker

thermal energy is the answer