A motor car is going due north at a speed of 50 km/h. It makes a 90° left turn without changing the speed. The change in the velocity of the car is about.

1. 50 km/h towards west

2. 70 km/h towards south-west

3. 70 km/h towards north-west

4. zero

Consider the motion of the tip of the minute hand of a clock. In one hour:

Choose the correct option:
1. (a) and (b)
2. (b) and (c)
3. (c) and (d)
4. (a) and (d)