Answer:Train A is 90 m long and running at 72 km/h.
Train B is 120 m long and running at 36 km/h.
When the trains are running in opposite directions, their relative speed gets added: 72+36 = 108 km/h.
The total length of A and B = 90+120 = 210 m
So the time taken to cross each other = 210 m*60*60/108*1000m
= 7 seconds
Explanation:
Answer:
Explanation:
Magnitude of frictional force = μ mg
μ is either static or kinetic friction.
To start the crate moving , static friction is calculated .
a ) To start crate moving , force required = μ mg where μ is coefficient of static friction .
force required =.517 x 56.6 x 9.8 = 286.76 N .
b ) to slide the crate across the dock at a constant speed , force required
= μ mg where μ is coefficient of kinetic friction , where μ is kinetic friction
= .26 x 56.6 x 9.8 = 144.21 N .
Answer:
Explanation:
Given
mass of ice cube 
inclination 
Spring constant 
initial compression 
Suppose Initially the cube is at the datum and it moves h height after release
So Elastic Potential Energy of Spring will convert to Potential Energy of cube
so final Potential Energy will be 
Initial Potential Energy
B.Initially spring is at compression so energy associated with it is its Elastic Potential Energy i.e. 0.125 J
Final Energy
Answer:
15.45 m/s
Explanation:
F = 1.2 x 10^3 N, Fk = 615 N, u = 0, s = 25 m
Let the speed after traveling 25 m is v.
mass = F / g = 1200 / 9.8 = 122.45 kg
Net force, Fnet = 1.2 x 1000 - 615 = 1200 - 615 = 585 N
acceleration = Fnet / mass = 585 / 122.45 = 4.78 m/s^2
Use third equation of motion
v^2 = u^2 + 2 a s
v^2 = 0 + 2 x 4.78 x 25 = 238.88
v = 15.45 m/s
