Answer:
a) 17.49 seconds
b) 13.12 seconds
c) 2.99 m/s²
Explanation:
a) Acceleration = a = 1.35 m/s²
Final velocity = v = 85 km/h = 
Initial velocity = u = 0
Equation of motion

Time taken to accelerate to top speed is 17.49 seconds.
b) Acceleration = a = -1.8 m/s²
Initial velocity = u = 23.61\ m/s
Final velocity = v = 0

Time taken to stop the train from top speed is 13.12 seconds
c) Initial velocity = u = 23.61 m/s
Time taken = t = 7.9 s
Final velocity = v = 0

Emergency acceleration is 2.99 m/s² (magnitude)
Answer:
The magnitude of the tension in the cable, T is 1,064.315 N
Explanation:
Here we have
Length of beam = 4.0 m
Weight = 200 N
Center of mass of uniform beam = mid-span = 2.0 m
Point of attachment of cable = Beam end = 4.0 m
Angle of cable = 53° with the horizontal
Tension in cable = T
Point at which person stands = 1.50 m from wall
Weight of person = 350 N
Therefore,
Taking moment about the wall, we have
∑Clockwise moments = ∑Anticlockwise moments
T×sin(53) = 350×1.5 + 200×2
T = 850/sin(53) = 1,064.315 N.
Answer:

Explanation:
We need to find the frequency of green light having wavelength o
. It can be calculated as follows :

So, the required frequency of green light is equal to
.
Answer: 65.25 J
Explanation:
Kinetic Energy K.E. = 1/2 * m * v^2 ; where m is the mass of the body and v is the velocity of the body ; K.E. = 1/2 * 0.145 * 30 * 30 = 65.25 Joules