Question
A contestant in a winter sporting event pushes a 45.0-kg block of ice across a frozen lake as shown in Figure 5.21(a). (a) Calculate the minimum force F he must exert to get the block moving. (b) What is the magnitude of its acceleration once it starts to move, if that force is maintained?
Question Image Figure 5.21 A person (a) pushing, and (b) pulling, a block of ice across ice.
1. $50\textrm{ N}$
2. $0.7 \textrm{ m/s}^2$
Solution Video

# OpenStax College Physics Solution, Chapter 5, Problem 18 (Problems & Exercises) (6:56) Rating

3 votes with an average rating of 3.7.

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Submitted by raynellmcclellan on Tue, 05/19/2020 - 11:47

Why do given the solution as 50 if it comes out as 51. Are we suppose to be rounding to the nearest tenth?

Submitted by ShaunDychko on Wed, 05/20/2020 - 15:43

Yes, exactly, we're rounding to one significant figure. This is due to the of the coefficient of static friction, which has only one significant figure. When multiplying by a number with one sig. fig., the answer gets only one sig. fig. also.
All the best,
Shaun