Chapter 8.5, Problem 26E

a.

To determine

To explain: the way to increase the horizontal forward force without increasing the total force.

Answer to Problem 26E

Decreasing the angle

Explanation of Solution

Given information:

Angle of $60°$ with the ground is made while pushing the handle of a lawn-mover.

Calculation:

Lowering the angle will increase the $x$ component of the force. The sketch of the given situation is shown below.

  

Thus the horizontal forward force can be increased without increasing the total force by decreasing the angle.

b.

To determine

To explain: the disadvantages of increasing the horizontal forward force without increasing the total force.

Answer to Problem 26E

It will cause back pain and muscle cramps

Explanation of Solution

Given information:

Angle of $60°$ with the ground is made while pushing the handle of a lawn-mover.

The $x$ component of the force increases by decreasing the angle. The sketch of the given situation is shown below.

  

Calculation:

Lowering the angle means the person has to change his or her posture. Thus it will cause back pain and muscle cramps.