Question

a block moving with speed 20m/s come to rest after 4s if the mass of block is 2kg .find the resistive force acting on the block​

Answer 1

Answer:

states that the acceleration of an object increases with increased force and decreases with increased mass. ... Notice how mass and force affect acceleration. Newton's second law. The acceleration of an object increases with increased force, decreases with increased mass, and is in the same direction as the force.

Explanation:

Area under the F−t graph gives the change in momentum of the block.

Area A = Area of triangle ABO - Area of triangle DCO

∴ A=  2 1  (4)(3)−  2 1 (2)(1.5)=4.5 Ns  

Initial momentum of the block P  

i  =0

Using  A=P  f−P  i

​⟹ P  f =4.5 Ns

Thus final kinetic energy of the block  K  f

​ =  2m P  f2

​⟹  K  f

=  2(2) (4.5)  2 =5.06J

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