# Three problems: Motion and equilibrium, Force, acceleration

16. The average speed of nitrogen molecule in air is about 6.70x10^2m/s, and its mass is 4.68x10^(-26) kg

a) If it takes 3.00x10^-13s for a nitrogen molecule to hit a wall and rebound with the same speed but opposite direction, what is the average acceleration of the molecule during this time interval

b)What average force does the molecule exert on the wall?

18. A bag of cement weigh 325N hangs in equilibrium from three wires as suggested of the picture below. Two of the wires make angle theta 1=60 degree, theta2=25 degree with the horizontal. Find the tension T1, T2 and T3 of the wires.

19. Based of the picture above to. A bag of cement weigh Fg hang in equilibrium from three wires as shown. Two of the wires make angles theta1, theta2 with the horizontal. Show that the tension on the left hand wire is

T1= (Fg.costheta2)/(sin(theta1+theta2))

https://brainmass.com/physics/equilibrium/three-problems-motion-and-equilibrium-force-acceleration-205226

#### Solution Summary

1. The average acceleration of nitrogen molecule at the time of collision is calculated.

2. Tensions in the strings for a hanging block is calculated.

3. Expression of tension in a wire is derived.

Set of three problems on Newton's laws of motion

1) A window washer of mass M is sitting on a platform suspended by a system of cables and pulleys as shown (see attachment). He is pulling on the cable with a force of magnitude F . The cables and pulleys are ideal (massless and frictionless), and the platform has negligible mass.

Find the magnitude of the minimum force that allows the window washer to move upward. Express your answer in terms of the mass and the magnitude of the acceleration due to gravity .

2) Two blocks with masses M1 and M2 hang one under the other. For this problem, take the positive direction to be upward, and use g for the magnitude of the acceleration due to gravity.

A) Find T2, the tension in the lower rope. Express your answer in terms of some or all of the variables M1, M2 ,and g.

B) Find T1, the tension in the lower rope. Express your answer in terms of some or all of the variables M1, M2 ,and g.

C) Find T2, the tension in the lower rope. Express your answer in terms of some or all of the variables M1, M2 ,a, and g.

D) Find T1 , the tension in the upper rope. Express your answer in terms of some or all of the variables

3) A wedge with an inclination of angle rests next to a wall. A block of mass m is sliding down the plane, as shown (see attachment). There is no friction between the wedge and the block or between the wedge and the horizontal surface.

A) Find the magnitude, Fnet , of the sum of all forces acting on the block. Express Fnet in terms of theta and m along with any necessary constants.

B) Find the magnitude, Fww , of the force that the wall exerts on the wedge. Express in terms of theta and m along with any necessary constants

See attached file for full problem description.

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