Question

A 2-kg block slides along a rough horizontal surface and slows to 10 m/s after traveling 20 m. If the kinetic coefficient of friction between the block and surface is 0.2, the initial speed (m/s) of the block was most nearly O a) 10.0 m/s ob) 10.4 m/s O c) 13.4 m/s od) 20.0 m/s

Question 2

Answer 1

1) given data:

mass of block (m) = 2 kg

final velocity of block (V') = 10 m/s

distance travelled (d) = 20 m

coefficient of kinetic friction ($\mu$) = 0.2

let the initial velocity of block be V

mg au ա 0 NTI — - NTI 10 m/s N

friction force = $\mu$ N

= $\mu$ *mg

= 0.2*2*9.81

= 3.924 N

from netwon's second law

f = m*a

a = f/m

= 3.924/2

= 1.962 m/s²

now from equation of motion

V'² = V² - 2*a*d

10² + 2*1.962*20 = V²

V = 13.359 m/s

thus correct option is c

2)

• hydrodynamic bearings are challenging to design for an average machinery designer. thus this statement is true.
• bearings are selected rather than being designed.so this statement is false
• bushing, journal bearing and rolling element bearing are all types of bearing thus this statement is also correct.
• both radial and axial loaded rolling element bearing are type of bearing and uses rolling element. thus this statement is also true.

thus correct option is b