Please help me! I have a lot going on today (I wont go into it), but if you coul

Question

Please help me! I have a lot going on today (I wont go into it), but if you could please help me with this I would be forever grateful.

A 98 kg box rests on a level surface as shown in Figure 1. The coefficient of static friction, µS = 0.8 and the coefficient of kinetic friction, µK = 0.4 .

Figure 1
a.) What is the magnitude of FGravity on box from Earth ?
N

b.) What is the magnitude of FNormal on box from surface ?
N

c.) What is the magnitude of Ffriction on box from surface ?
N
Mighty Mouse arrives and gives the box a 538 N horizontal push as shown in Figure 2.

Figure 2
d.) Now what is the magnitude of Ffriction on box from surface ?
N

Mighty Mouse decides to push a little harder and gives the box a 691 N horizontal push.
e.) Now what is the magnitude of Ffriction on box from surface ?
N

Again Mighty Mouse decides to push a little harder and gives the box a 768 N horizontal push.
f.) Now what is the magnitude of Ffriction on box from surface ?
N

Once again Mighty Mouse decides to push a little harder and gives the box a 845 N horizontal push.
g.) Now what is the magnitude of Ffriction on box from surface ?
N

Explanation / Answer

SAME QUESTION QITH DIFFERENT NUMBERS : please Rate me !! the solutions are correct . u just have to put in ur numbers ! A 92 kg box rests on a level surface as shown in Figure 1. The coefficient of static friction, µS = 0.9 and the coefficient of kinetic friction, µK = 0.5 . Figure 1 a) What is the magnitude of FGravity on box from surface ? b) What is the magnitude of FNormal on box from Earth ? c) What is the magnitude of Ffriction on box from surface ? Mighty Mouse arrives and gives the box a horizontal push d) If Mighty Mouse pushes with a force of 568 N, what is the magnitude of Ffriction on box from surface ? e) If Mighty's force on the box is 730 N. What is the magnitude of Ffriction on box from surface ? f) Suppose Mighty Mouse uses an even larger horizontal force of 811 N. What would be the magnitude of Ffriction on box from surface ? g) If Mighty's force on the box is 893 N, what is the magnitude of Ffriction on box from surface ? answer 1 :: a) mag Fgrav = 92kg * 9.8m/s² = 902 N b) mag Fn = 902 N c) Ff = 0 (no lateral forces) d) static Ff = µmg = 0.9 * 92kg * 9.8m/s² = 811 N The applied force does not overcome this, so Ff = Fapp = 568 N e) Same logic; Ff = 730 N f) Same logic; Ff = 811 N (ANY more force and the box would start to move and Ff would drop) g) At Fapp > 811 N, Ff = µmg = 0.5 * 92kg * 9.8m/s² = 451 N Answer 2 : a) Weight = mg = 92 x 9.8 = 901.6 N vertically down ... they just want the magnitude ... so 901.6 N b) The box is on a level surface so: F(normal) = 901.6 N vertically up ? so the magnitude is 901.6 N c) The box is at rest on a level surface so there is no resultant horizontal force acting on the box No horizontal force is applied to the box ... so the magnitude of F(friction) is zero d) F(friction) = µ * F(normal) The maximum frictional force between the box and the surface (just b4 the box starts to move) is: Max F(friction) = 0.9 x 901.6 = 811.44 N (in the direction that opposes motion) ... using µ(static) b/c the box is at rest The applied force is 568 N

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