Answer:
Option B is the correct answer.
Explanation:
Shear stress is the ratio of shear force to area.
We have
Shear stress = 3 N/mm² = 3 x 10⁶ N/m²
Area = Area of rectangle = 10 x 10⁻² x d = 0.1d
Shear force = 50000 N
Substituting

Width of beam = 16.67 cm
Option B is the correct answer.
The correct answer to the question is- 
CALCULATION:
As per the question, the electric field generated by the source charge is 1236 N/C at a distance of 4 m.
Hence , electric field E = 1236 N/C.
The distance of the point R = 4m
We are asked to calculate the charge possessed by the source.
The electric field produced by a source charge of Q at a distance R is calculated as -
Electric field E = 
Here,
is called the absolute permittivity of the free space.
Hence, the charge of source is calculated as -
Q = 
= 
= 
= 
= 
Hence, the charge of source is 
Answer:
(a). The initial velocity is 28.58m/s
(b). The speed when touching the ground is 33.3m/s.
Explanation:
The equations governing the position of the projectile are


where
is the initial velocity.
(a).
When the projectile hits the 50m mark,
; therefore,

solving for
we get:

Thus, the projectile must hit the 50m mark in 1.75s, and this condition demands from equation (1) that

which gives

(b).
The horizontal velocity remains unchanged just before the projectile touches the ground because gravity acts only along the vertical direction; therefore,

the vertical component of the velocity is

which gives a speed
of


Answer:
The magnitude of the rate of change of the child's momentum is 794.11 N.
Explanation:
Given that,
Mass of child = 27 kg
Speed of child in horizontal = 10 m/s
Length = 3.40 m
There is a rate of change of the perpendicular component of momentum.
Centripetal force acts always towards the center.
We need to calculate the magnitude of the rate of change of the child's momentum
Using formula of momentum


Put the value into the formula


Hence, The magnitude of the rate of change of the child's momentum is 794.11 N.
Answer:
0.68 m
Explanation:
α = dL / L1*(dT)
dL = L1(dT) * α
Initial length, L1 = 100
Chang in Length =dL
α linear expansivity ; dL = change in length ; dT = change in temperature ; L1 = initial length
α of iron rod = 1.13 * 10^-5 k
dL = 100(40 - 10) * 1.13 * 10^-5
dL = 100(30) * 1.13 * 10^-5
dL = 3000 * 1.13 * 10^-5
dL = 3390 * 10^-5
dL = 0.0339 m
Error :
Distance measured = 2km = (2 * 1000) = 2000m
[Distance measured / (initial length + change in length)] × change in length
Error = (2000 / (100 + 0.0339)) * 0.0339
Error = (2000 / 100.0339) * 0.0339
Error = 19.993222 * 0.0339
Error = 0.6777702
Error = 0.68 m