Answer:
400 N
Explanation:
By the law of friction,
is the maximum frictional force, 
is the coefficient of friction and 
is the reaction on the refrigerator. On a horizontal surface, the reaction is equal to the weight of the refrigerator.
While not moving, the fricition on the refrigerator is static friction. So, 
This is the maximum frictional force and is more than the applied horizontal force of 400 N. Frictional force cannot be more than the applied force, else it would actually pull the refrigerator backwards (a strange thing, if it were to happen). It is equal to the extent of the applied force because the applied force is not enough to overcome the maximum.
Hence the frictional force is 400 N.
PS: Note that we do not use the coefficient of kinetic friction because applied force could not overcome the static friction.
Answer:
Explanation:
Mass of nails is 0.25kg
Mass of hammer 5.2kg
Speed of hammer is =52m/s
Then, Ben kinetic energy is given as
K.E= ½mv²
K.E= ½×5.2×52²
K.E= 7030.4J
Given that, two-fifth of kinetic energy is converted to internal energy
Internal energy (I.E) = 2/5 × K.E
Internal energy (I.E) = 2/5 × 7030.4
I.E=2812.16J.
Energy increase is total Kinetic energy - the internal energy
∆Et= K.E-I.E
∆Et= 7030.4 - 2812.16
∆Et= 4218.24J
Answer:
it is the impact of a meteorite, volcanic activity, or an explosion.
Well there is many ways we are not evolved as much as we think we are from being we die from a lot of diseases to world hunger and other things to be honest humans are far from being really evolved in life we really need to focus on cures and solving world hunger and fighting among ourselves
Hope this helps
