Question

(Figure 1)shows a 250 g hamster sitting on an 750 g wedge-shaped block. The block, in turn, rests on a spring scale. An extra-fine lubricating oil having μs=μk=0 is sprayed on the top surface of the block, causing the hamster to slide down. Friction between the block and the scale is large enough that the block does not slip on the scale.

Scale

1. What does the scale read, in grams, as the hamster slides down? Express your answer with the appropriate units.

Answer 1

1.

m_h = mass of hamster = 250 g = 0.250 kg

m_b = mass of block = 750 g = 0.750 kg

N = scale reading

Consider hamster and block as a single entity

the force by the scale in upward direction balances the weight of entity, hence

N = (m_h + m_b) g

N = (0.250 + 0.750) (9.8)

N = 9.8 N