W=Fd
W is work
F is force in newtons
D is displacement in meters
W= 25 x 3
W= 75Nm
Answer:
Explanation:
When the spring is compressed by .80 m , restoring force by spring on block
= 130 x .80
= 104 N , acting away from wall
External force = 82 N , acting towards wall
Force of friction acting towards wall = μmg
= .4 x 4 x 9.8
= 15.68 N
Net force away from wall
= 104 -15.68 - 82
= 6.32 N
Acceleration
= 6.32 / 4
= 1.58 m / s²
It will be away from wall
Energy released by compressed spring = 1/2 k x²
= .5 x 130 x .8²
= 41.6 J
Energy lost in friction
= μmg x .8
= .4 x 4 x 9.8 x .8
= 12.544 J
Energy available to block
= 41.6 - 12.544 J
= 29 J
Kinetic energy of block = 29
1/2 x 4 x v² = 29
v = 3.8 m / s
This will b speed of block as soon as spring relaxes. (x = 0 )
Explanation:
The two postulates of special theory of relativity
Postulate 1: The law of physics are invariant under any of inertial frame of reference.
Postulate 2: The velocity of light is remains same in each ans every frame of reference and independent of relativity.
They are differ from classical mechanics that in classical mechanics there is no change in mass and length in relative velocity but in relativistic mechanics it changes.
These two postulates implements in phenomenon like time dilation , length contraction etc.
Thanks
For the first part of the trip:
we have velocity = 960 km/hr and distance = 2250 km
velocity = distance / time
time1 = distance / velocity = 2250 / 960 = 2.34375 hours
For the second part of the trip:
we have velocity = 805 km/hr and distance = 1320 km
velocity = distance / time
time2 = distance / velocity = 1320 / 805 = 1.63975 hours
For the total trip:
we have:
total distance covered = 2250 + 1320 = 3570 km
total time taken = 2.34375 + 1.63975 = 3.9835 hours
average velocity = total distance / total time
average velocity = 3570 / 3.9835 = 896.1968 km/hr