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1. Think and name a situation in which: 1. Kinetic friction does positive work 2. Static friction
does positive work 3. Air resistance does positive work 4. A normal force does negative work 5.
A normal force does positive work 6. Tension does positive work 7. Tension does negative work
8. Tension does zero work
Solution
1.Kinetic Energy does positive work-person speeding up while running
2.Static friction does positive work - static friction on Block B kept on block A moving with
some accleration a
3.Air resistance does positive work-Wind blowing in direcion of motion of body
4.A normal does negative work=A Normal force on person in lift going up with acceleration a
5.A normal does positive work=A Normal force on person in lift coming down with acceleration
a
6.Tension does positve work=A block going up with rope tied to it
7.Tension does negative work=A block coming down with rope tied to it
8.Tension does zero work=A block hanged with rope and it is at rest