Chapter 7
Work, Energy, and Simple Machines
CBSE Class 9
Science Solutions
Educart Science class Class 9 NCERT Exemplar cover
Question:

Is the work done by friction on the stack of coins that travels on a rough surface (positive, negative or zero)?[Pg. No. 119]

Answer: Verified

The work done by friction on the stack of coins moving on a rough surface is negative. This is because the frictional force acts opposite to the direction of motion of the coins, thereby reducing their speed.

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More NCERT Questions
Explain why roads on hills are built to wind around in gentle slopes rather than going straight up? [Pg. No. 132] Why is it easier to open the lid of a can by using a spoon as shown in Figure.[Pg. No. 135] To reach a higher floor, we find climbing an inclined ladder easier in comparison to climbing a vertical ladder. Explain why.[Pg. No. 132] State whether True or False. (A) Work is said to be done when a force is applied, even if the object does not move. (B) Lifting a bucket vertically upward results in positive work done on the bucket.