A 2.20 kg steel block is at rest on a steel table. A horizontal string pulls on
ID: 1340884 • Letter: A
Question
A 2.20 kg steel block is at rest on a steel table. A horizontal string pulls on the block. The coefficient of static friction of dry steel on steel is s=.800, the coefficient of kinetic friction of dry steel on steel is k,dry=.600, and the coefficient of kinetic friction of lubricated steel on steel is k,lube=.050.
What is the minimum string tension needed to move the block?
If the string tension is 20.0 N , what is the block's speed after moving 1.00 m ?
If the string tension is 20.0 N and the table is coated with oil, what is the block's speed after moving 1.00 m ?
Explanation / Answer
a)
T = s*N = s*mg
Tmin = 0.80*2.20*9.8 = 17.24 N
b)
in case of motion kinetic friction will act
and T - k*mg = ma
20 - 0.6*2.20*9.8 = 2.20a
=> a = 3.21 m/s^2
V^2 = U^2 + 2aS
=> V^2 = 0 + 2*3.21*1
=> V = 2.53 m/s
c)
in this case of motion kinetic friction will act with value 0.050
and T - k*mg = ma
20 - .050*2.20*9.8 = 2.20a
=> a = 8.6 m/s^2
V^2 = U^2 + 2aS
=> V^2 = 0 + 2*8.6*1
=> V = 4.14 m/s
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.