Basic CS [3i Infotech Placement]: Sample Questions 4 - 5 of 243

Glide to success with Doorsteptutor material for competitive exams : get questions, notes, tests, video lectures and more- for all subjects of your exam.

Question 4

Write in Short Short Answer▾

If a binary tree has 20 nodes then it has how many null branches?

Edit

Explanation

  • A binary tree with 20 nodes has 21 many null branches.
  • Consider, a tree with 5 nodes (n = 5)
  • No. of null pointer = 2n- (n-1) = n + 1
  • When , n = 20
  • Then n + 1 = 20 + 1 = 21

Question 5

Question MCQ▾

When a bicycle is in motion, the force of friction exerted by the ground on the two wheels is such that it acts

Choices

Choice (4)

a.

In the forward direction on the front wheel and in the backward direction on the rear wheel.

b.

In the backward direction on both the front and rear wheels.

c.

In the backward direction on the front wheel and in the forward direction on the rear wheel.

d.

Question does not provide sufficient data or is vague

Edit

Answer

b.

Explanation

  • Pedalling the bicycle merely rotates the back wheel in clockwise sense.
  • The velocity of point of contact is therefore backwards, so, friction must act forward on the rear wheel.
  • This frictional force causes a translational acceleration of the entire bicycle, including the front wheel.
  • The velocity of point of contact tends to develop in the forward direction so friction acts in the backward direction.

Similar reasoning applies to a car, for the engine merely rotates the back wheel.