First determine the net force. Let's say the downwards force is negative and the upwards force is positive.
Since the forces act in opposite directions, the net force would be:
400N - 600N = -200N
Since I said negative is downwards, this translates to the net force being 200N downwards.
Force = mass*acceleration
200N = 60kg * acceleration
acceleration = 3.33 m/s^2
Answer:
(a) Elongation of the rod==5.61×10⁻⁹m
(b) Change in diameter=1.640×10⁻⁸m
Explanation:
Given data
Diameter d=78 in=1.9812 m
Cross Area is:

Applied Load P=17 KN=17×10³N
E=29 × 106 psi=1.99947961×10¹¹Pa
Stress and Strain in x direction
Stress in x direction
σ=P/A

σ=5517.25 Pa
Strain in x direction
ε=σ/E

ε=2.76×10⁻⁸
Part (a)
Elongation of the rod=Lε
=(0.2032)(2.76×10⁻⁸)
Elongation of the rod==5.61×10⁻⁹m
Part(b) Change in diameter
Strain in y direction
ε₁= -vε
ε₁= -(0.30)(2.76×10⁻⁸)
ε₁=-8.28×10⁻⁹
Change in diameter=d×ε₁
Change in diameter=(1.9812m)×(-8.28×10⁻⁹)
Change in diameter=1.640×10⁻⁸m
Answer:
B can take 0.64 sec for the longest nap .
Explanation:
Given that,
Total distance = 350 m
Acceleration of A = 1.6 m/s²
Distance = 30 m
Acceleration of B = 2.0 m/s²
We need to calculate the time for A
Using equation of motion

Put the value in the equation



We need to calculate the time for B
Using equation of motion
Put the value in the equation



We need to calculate the time for longest nap
Using formula for difference of time



Hence, B can take 0.64 sec for the longest nap .
I’m pretty sure the answer is c and d hope this helps and good luck