EasyPhysicsHigh School (11–12)Mechanics › Vectors and Motion in a PlaneNumericalBoard ExamAPA-LevelIB
A gardener pushes a heavy lawn roller along level grass…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A gardener pushes a heavy lawn roller along level grass. She pushes along the handle with a force of , and the handle slopes down towards the roller at below the horizontal.
- How much of her push moves the roller forward?
- How much of it presses the roller down into the grass?
Need a reminder? The key ideaShow
With the angle measured from the horizontal, a force has a horizontal part and a vertical part:
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. , at below the horizontal.
Plan. Split the push into a part along the ground and a part straight down.
Step 1. Forward. .
Step 2. Down. , downwards.
Answer: forward, and down into the grass.
Check. . The two parts give back the push.
What if? If she pulled the roller instead, with the handle at above the horizontal, the vertical part would lift the roller instead of pressing it down. That is why pulling a roller is easier than pushing it.
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