Answer:
distance between school and home is 21 miles
Explanation:
given data
in rush hour speed s1 = 28 mph
less traffic speed s2 = 42 mph
time t = 1 hr 15 min = 1.25 hr
to find out
distance d
solution
we consider here distance home to school is d and t1 time to reach at school
we get here distance equation when we go home to school that is
distance = 28 × t1 .......................1
and when we go school to home distance will be
distance = 42 × ( t - t1 )
distance = 42 × ( 1.25 - t1 ) ...................2
so from equation 1 and 2
28 × t1 = 42 × ( 1.25 - t1 )
t1 = 0.75
so
from equation 1
distance = 28 × t1
distance = 28 × 0.75
distance = 21 miles
Answer:
317.52 mi/hr
Explanation:
First convert Meters into miles as the answer is required in miles/ h
1000m = 0.62 mi
Now, convert second into hours
7.45s = 0.0001 hr
The speed of the boat would be
v = 0.62/0.0001
=317.52 mi/hr
As per the question the initial speed of the car [ u] is 42 m/s.
The car applied its brake and comes to rest after 5.5 second.
The final velocity [v] of the car will be zero.
From the equation of kinematics we know that
[ here a stands for acceleration]



Here a is taken negative as it the car is decelerating uniformly.
We are asked to calculate the stopping distance .
From equation of kinematics we know that
[here S is the distance]
![= 42*5.5 +\frac{1}{2} [-7.64] [5.5]^2 m](https://tex.z-dn.net/?f=%3D%2042%2A5.5%20%2B%5Cfrac%7B1%7D%7B2%7D%20%5B-7.64%5D%20%5B5.5%5D%5E2%20m)
[ans]
E=hf C=wavelength*F
E=hC/wavelength
E=(6.626*10^-34)*(3.00*10^8)/670*10^-9
E=(6.626*10^-34)*(3.00*10^8)/450*10^-9
Answer:
0.8895m
Explanation:
Cable diameter = 0.0125m
Mass of elevator = 6450kg
Young Modulus(E) = 2.11*10¹¹N/m
∇l (change in length) =
L = 362m
A = Πr², but r = d / 2 = 0.0125 / 2 = 0.00625m
A = 3.142 * (0.00625)² = 1.227*10^-4m²
Young Modulus (E) = Tensile stress / Tensile strain
E = (F / A) / ∇l / L
F = mg = 6450 * 9.8 = 63210N
2.11*10¹¹ = (63210 / 1.22*10^-4) / (∇l / 362)
2.11*10¹¹ = 5.18*10⁸ / (∇l / 362)
2.11*10¹¹ = (5.18*10⁸ * 362) / ∇l
2.11*10¹¹ = 1.875*10¹¹ / ∇l
∇l = 1.875*10¹¹ / 2.11*10¹¹
∇l = 0.8895m
The change in length is 0.8895m