Question

An object starting from rest obtains a speed of 54km/h after 10s. If the mass of the object is 1kg, calculate (i) The initial momentum of the object (ii) Final momentum of the object (iii) External unbalanced force acting on the object

Answer 1

Answer:

(i) 0 kg m/s  (ii) 15kg m/s   (iii)F= 1.5 N

Explanation:

U ( initial velocity) = 0m/s (Because it starts from rest)

v (final velocity) = 54km/hr (convert into m/s = 15 m/s)

t = 10s

m = 1kg

(i) The initial momentum of the object = mu = 1 x 0 = 0 kg m/s

(ii) Final momentum of the object = mv = 1 x 15 = 15kg m/s

(iii) External unbalanced force acting on the object =   F=ma

       m=1kg

       acceleration =v-u/t

  a =15 - 0 /10

  a = 1.5 m/s^2

Force = Mass x acceleration

          = 1 x 1.5

unbalanced force acting on the object         = 1.5 N (0R) 1.5 Kg m/s2

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