Author Question: A 25-kg block on a horizontal surface is attached to a light spring (force constant = 8.0 kN/m). The ... (Read 143 times)

yoooooman · **on:** Jul 28, 2018

A 25-kg block on a horizontal surface is attached to a light spring (force constant = 8.0 kN/m). The block is pulled 10 cm to the right from its equilibrium position and released from rest. When the block has moved 2.0 cm toward its equilibrium position, its kinetic energy is 12 J. What is the change in mechanical energy caused by the frictional force on the block as it moves the 2.0 cm?
a. -4.0 J
b. -3.5 J
c. -2.4 J
d. -2.9 J
e. -15 J

Question 2

A 2.0-kg mass is projected vertically upward from ground level with an initial speed of 30 m/s. The mass rises to a maximum height of 35 m above ground level. What is the change in mechanical energy of the mass caused by air resistance between the point of projection and the point of maximum height?
a. -0.21 kJ
b. -0.47 kJ
c. -0.40 kJ
d. -0.34 kJ
e. -0.69 kJ