Answer:
The minimum force the climber must exert is about 439N.
Explanation:
We use the relationship between friction and normal force to answer this question:
![F_{friction} = \mu_{static} \cdot F_{normal}\implies F_{normal}=\frac{F_{friction}}{\mu_{static}}](https://tex.z-dn.net/?f=F_%7Bfriction%7D%20%3D%20%5Cmu_%7Bstatic%7D%20%5Ccdot%20F_%7Bnormal%7D%5Cimplies%20F_%7Bnormal%7D%3D%5Cfrac%7BF_%7Bfriction%7D%7D%7B%5Cmu_%7Bstatic%7D%7D)
We are given the static coefficients of friction but need to determine the friction force. To do that we consider the totality of forces acting on this hapless gentleman stuck in a chimney. There is the gravity acting downward (+), then there are two friction forces acting upward (-), namely through his shoes and his back. The horizontal force exerted by the climber on both walls of the chimney is the same and is met with equally opposing normal force. Since the climber is not falling the net force in the vertical direction is zero:
![F_{net} = 0 = F_g - F_{shoes}-F_{back}= mg - \mu_{shoes}F_{norm}-\mu_{back}F_{norm}\\F_{norm}=\frac{mg}{\mu_{shoes}+\mu_{back}}=\frac{64.5kg\cdot 9.8\frac{m}{s^2}}{0.8+0.64}\approx 438.96N\\](https://tex.z-dn.net/?f=F_%7Bnet%7D%20%3D%200%20%3D%20F_g%20-%20F_%7Bshoes%7D-F_%7Bback%7D%3D%20mg%20-%20%5Cmu_%7Bshoes%7DF_%7Bnorm%7D-%5Cmu_%7Bback%7DF_%7Bnorm%7D%5C%5CF_%7Bnorm%7D%3D%5Cfrac%7Bmg%7D%7B%5Cmu_%7Bshoes%7D%2B%5Cmu_%7Bback%7D%7D%3D%5Cfrac%7B64.5kg%5Ccdot%209.8%5Cfrac%7Bm%7D%7Bs%5E2%7D%7D%7B0.8%2B0.64%7D%5Capprox%20438.96N%5C%5C)
The normal force in this equilibrium is about 439N and because we are told that the static friction forces are both at their maximum, this value is at the same time the <em>minimum</em> force needed for the climber to avoid starting slipping down the chimney.
Answer:
An ion.
Explanation:
Atoms can gain or lose electrons and become ions, which are atoms that have a positive or negative charge, because they have unequal numbers of protons and electrons.
Explanation:
Momentum is conserved.
a) In the first scenario, Olaf and the ball have the same final velocity.
mu = (M + m) v
(0.400 kg) (10.9 m/s) = (70.2 kg + 0.400 kg) v
v = 0.0618 m/s
b) In the second scenario, the ball has a final velocity of 8.10 m/s in the opposite direction.
mu = mv + MV
(0.400 kg) (10.9 m/s) = (0.400 kg) (-8.10 m/s) + (70.2 kg) v
v = 0.108 m/s
Answer:
<h2>b) 4230 J
</h2>
Explanation:
Step one:
given data
extension= 40cm
Spring constant K= 52.9N/cm
Step two:
Required
the Kinetic Energy KE
the expression to find the kinetic energy is
KE= 1/2ke^2
substituting our data we have
KE= 1/2*52.9*40^2
KE=0.5*52.9*1600
KE= 42320Joules
<u>The answer is b) 4230 J
</u>
, to hit nails into a piece of wood or a wall, or to break things into pieces.