# Applying Force On An Angle

Gold Member

## Homework Statement

A lawnmower weighing 20kg has a handle attached at 35 degrees to the horizontal. If a man wishes to push the lawnmower, so that after 2.5s, its velcoity is 2 m/s, what force should he apply along the handle.

## Homework Equations

$$\sum {\overrightarrow F } = m\overrightarrow a$$

## The Attempt at a Solution

ok, since after 2.5 seconds, it requires a velocity of 2 m/s, i found the acceleration of the mower to be 0.8 m/s/s. Since it has a mass of 20kg, the net force applied must then be:

$$\sum {\overrightarrow F } = 20 \times 0.8 = 16N$$

So the horizontal component of the force he applies must be 16N in the direction of acceleration.

The horizontal component of the force (F) he applies down the handle will be $$F cos 35$$. So solving for F:

$$Fcos35=16$$

Gives F=19.5N.

According to the answer book, the answer is 120N. Where have i gone wrong?

Thanks,
Dan.

Last edited:

Hootenanny
Staff Emeritus
Gold Member
If the question is quoted correctly, then I would agree with your answer. Does the text not mention any other factors, such as friction?

Gold Member
Nope, no friction at all. What ive said is pretty much quoted word for word from the book.