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konichiwa2x
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The answer is it is easier to pull a lawnmover than to push it. I understand it logically but how do you prove it? My teacher says it has something to do with resolution of vectors. Can someone please explain?
I don't think it makes any difference at all if it has good wheels. The normal force is different depending on whether it is being pushed or pulled (assuming you are doing this by way of a handle inclined at an angle greater than 0 to the horizontal), but this should not affect the force required to move it, if it has proper wheels.konichiwa2x said:The answer is it is easier to pull a lawnmover than to push it. I understand it logically but how do you prove it? My teacher says it has something to do with resolution of vectors. Can someone please explain?
I see your point about the torque, but why would it increase friction when you pushed down on the mower if it has proper wheels?Chi Meson said:The classic answer has to do with the fact that as you push the handle you are pushing down slightly, and if you pull the handle, you pull up slightly. These actions would increase and decrease the normal force respectively (this increase/decrease friction). But, as anyone who has ever cut grass should know, when pushing, you push the handle horizontally. Sometimes the push is slighly up, isn't it? Depending on the push you will introduce a torque to the system and more normal force will be on one set of wheels (usually the front).
In other words, this is a classic problem that fails completely in the real world. Other factors completely obliterate the expected effect.
Wheels with bearings.Office_Shredder said:If you push down on the mower, there is a greater normal force between the wheels and the shaft.
What kind of super wheels are you using that have zero friction?
Most of us don't like walking backward. It is easier to pull it with one hand. The point here is that the difference in normal force between pushing and pulling will have virtually no effect on the frictional energy loss in horizontal motion, if the mower has proper wheels (good bearings).pallidin said:Not only that, but have you noticed a tendency for one to "push" a lawnmover with both hands, yet pull it backwards with only one?
Ideally, the increase in normal force would increase the friction, but in the real world the resulting increase in friction in the wheel bearings would be so insignificant, even if the bearings were not that great. Other factors, already mentioned, are far more significant in determining which way is easier.Andrew Mason said:I see your point about the torque, but why would it increase friction when you pushed down on the mower if it has proper wheels?
AM
I think the point is not so much about the friction of the wheel bearings, it's due to the softness of the grass and dirt. On a hard surface, yeah, with good wheel bearings there would be a trivial difference in effort. But on soft grass, I think there is probably a measurable difference. Well, except for the good point that mowing backwards would be obnoxious...Office_Shredder said:Good bearings reduce, not eliminate, friction.
And most lawnmowers are not made with great bearings (if any).
Not quite. First of all, I assume the "cos" refers to a componant of the weight of the lawnmower, where the angle is that of the handle with the horizontal. Rather than looking at components along the handle, look at the components that are horizontal and vertical:konichiwa2x said:Maybe I should have rephrased the question. The lawnmover is moving on a flat ground. Let's assume there is no grass. Friction needs to be taken into account.
Anyway here is my view on this.
Let the force applied while pulling/pushing be F Newtons. While pushing the net force acting on the lawnmover is F + mgcos where 'm' is the mass of the lawnmover. While pulling mgcos acts opposite to the pull therefore the resultant force is F - mgcos. Therefore, the work done is less. and hence, it is easier to push than to pull.
Is this right??
The answer to this question depends on the type of lawnmower and the individual's personal preference. Some people may find it easier to push a lawnmower, while others may find it easier to pull it.
The type of lawn can have an impact on whether it's easier to push or pull a lawnmower. For example, if the lawn is flat and free of obstacles, it may be easier to push the lawnmower. However, if the lawn is hilly or has a lot of uneven terrain, pulling the lawnmower may be more efficient.
The weight of the lawnmower can play a role in whether it's easier to push or pull. Generally, lighter lawnmowers are easier to push, while heavier lawnmowers may require more effort to pull. However, this can also depend on the individual's strength and physical abilities.
Yes, there are some safety concerns to consider when pushing or pulling a lawnmower. When pushing, there is a risk of the lawnmower tipping over and causing injury. When pulling, there is a risk of the lawnmower rolling over the individual if they lose control. It's important to follow proper safety precautions and use caution when operating a lawnmower.
One technique for making it easier to push a lawnmower is to maintain proper posture and use your legs to generate power. For pulling a lawnmower, it can help to slightly tilt the lawnmower towards you and use your body weight to assist in pulling. It's also important to regularly maintain and sharpen the blades of the lawnmower to make pushing or pulling easier.