A box of mass 40kg rests on a flat horizontal surface. It is pulled by a constant horizontal force of 200N and the frictional force acting between the box and the horizontal surface is 120N.
2006-08-22 06:43:38 · 13 answers · asked by jeanpace89 1 in Education & Reference ➔ Homework Help
The four forces here will be
- weight of the box(Mg) downwards,
- the normal reaction from the surface on which the box stands (N) upwards,
- the friction (f, or coeff. of static or dynamic friction x N depending on whether the box is not about to move, about to move or moving - 120 N in this case) and
- the Force F (200N here) acting on the box.
Btw, I don't think its cool to get yr. HW answers from Yahoo ... I hope this wasn't some assignment prob or something.
Free Body diags are easy to draw ... just isolate the bodies in the system and then concentrate on each one separately.
Try using acceleration diagrams in conjunction with free body diagrams to solve probs in mechanics.
2006-08-22 07:04:04 · answer #1 · answered by RM 1 · 1⤊ 0⤋
1) Its weight due to the presence of its mass in an acceleration field (ie Newtons 2nd Law of motion, Force = mass x acceleration. the mass here is 40kg and the acceleration is 9.81m/s/s towards the earth.
2)Being on a horizontal surface and obeying Newtons 3rd Law of motion - to every action there is a reaction in essence - and thus assuming no vertical plane motion, there will be an equal and opposite directional force to that discussed in (1) exerted at the point of contact between the object and the surface.
3) The horizontal force being applied to the box (ie 200N). Easy huh?
4) The frictional force will act at the box / surface interface and in the opposite direction to the boxs' horizontal motion - by definition. Note since the box has been outlined to be moving, this is kinetic friction and not static friction. Don't confuse the two since static can in some cases be greater in value than kinetic, till it breaks down and becomes kinetic friction as the applied force is increased beyond its static threshold.
2006-08-22 06:59:00 · answer #2 · answered by frohike47 2 · 0⤊ 0⤋
Following should be shown in the free body diagram: the applied force of back of the chair pushing your little brother forward the force of gravity acting on your little brother the support force of the chair on your little brother the static friction between your little brother and the seat of the chair [The other forces are either not acting on the little brother or are applied by the little brother.] I have assumed that you are only pushing the back of the chair and not actually touching your brother. I think old prof is not correct; if no static frictional force is acting due to chair's surface, brother's butt will slip on the chair but that is not given in the problem
2016-03-27 01:17:58 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Gravity, Friction, the horizontal force (200N) and air resistance?
2006-08-22 06:50:37 · answer #4 · answered by Neil_R 3 · 1⤊ 0⤋
40kg (=392.4N) down as the weight of the box, 392.4N up as reactionary force of the ground, 200N in the direction of pull, and 120N in the oposite direction. Mmmm, isn't dynamics fun.
2006-08-22 06:56:27 · answer #5 · answered by Anonymous · 1⤊ 0⤋
Reactive force up, (equals same as weight)
Downward force (Weight ie mass*gravity),
Frictional force One horizontal force (Left say),
Constant horizontal force other horizontal force opposite direction to frictional force (Right say).
2006-08-23 02:24:18 · answer #6 · answered by Anonymous · 1⤊ 0⤋
gravity, normal reaction of the surface on which the body rests on the body, the pulling force, & the frictional force
2006-08-22 06:54:00 · answer #7 · answered by s_kundu88 3 · 0⤊ 0⤋
there is gravity(g) of (40*9.81)N and the reactional force (R) of (40*9.81)N upwards from the table on the object, the sideways force of 200N and the frictioiona. force of 120N
2006-08-22 10:07:46 · answer #8 · answered by Anonymous · 0⤊ 0⤋
There would be the normal force acting up, the gravitational force and then your pulling force and the force of friction.
2006-08-22 11:54:44 · answer #9 · answered by Magnetochemist 4 · 1⤊ 0⤋
When drawing a free body diagram, I would suppose the 4 forces involved would be (1) the pencil, (2) the sketch pad, (3) the pressure exerted, and (4) the body's resistance. There you have it. You're welcome. No charge.
2006-08-22 06:52:03 · answer #10 · answered by yahoohoo 6 · 0⤊ 0⤋