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