Q. No.A man is walking on a horizontal road with a speed of \(4\) km/h. Suddenly, the rain starts vertically downwards with a speed of \(7\) km/h. The magnitude of the relative velocity of the rain with respect to the man is:
1. \(\sqrt{33}\) km/h
2. \(\sqrt{65}\) km/h
3. \(8\) km/h
4. \(4\) km/h
1. \(45^\circ\)
2. \(30^\circ\)
3. \(60^\circ\)
4. \(90^\circ\)
A boat is moving with a velocity \(3\hat i + 4\hat j\) with respect to ground. The water in the river is moving with a velocity\(-3\hat i - 4 \hat j\) with respect to ground. The relative velocity of the boat with respect to water is:
1. \(8\hat j\)
2. \(-6\hat i-8\hat j\)
3. \(6\hat i+8\hat j\)
4. \(5\sqrt{2}\)
Raindrops are falling with speed \(v\) vertically downwards and a man is running on a horizontal road with speed \(u.\) The magnitude of the velocity of the raindrops with respect to the man is:
1. \(v-u\)
2. \(v+u\)
3. \(\sqrt{{v}^2 + {u}^2 \over 2}\)
4. \(\sqrt{{v}^2 + {u}^2}\)
A person, reaches a point directly opposite on the other bank of a flowing river, while swimming at a speed of \(5\) m/s at an angle of \(120^\circ\) with the flow. The speed of the flow must be:
1. \(2.5\) m/s
2. \(3\) m/s
3. \(4\) m/s
4. \(1.5\) m/s
A swimmer swims a distance d upstream in \(4\) s and swims an equal distance downstream in \(2\) s. The ratio of swimmer's speed in still water to the speed of river water will be:
| 1. | \(\frac{6}{5} \) | 2. | \(\frac{3}{1} \) |
| 3. | \(\frac{5}{3} \) | 4. | \(\frac{4}{3}\) |
A man standing on a road holds his umbrella at \(30^{\circ}\) with the vertical to keep the rain away. He throws the umbrella and starts running at \(10\) km/hr. He finds that raindrops are hitting his head vertically. The speed of raindrops with respect to the road will be:
1. \(10\) km/hr
2. \(20\) km/hr
3. \(30\) km/hr
4. \(40\) km/hr
A man can row a boat with a speed of \(10\) kmph in still water. The river flows at \(6\) kmph. If he crosses the river from one bank to the other along the shortest possible path, time taken to cross the river of width \(1\) km is:
1. \(\frac{1}{8}~\text{h}\)
2. \(\frac{1}{4}~\text{h}\)
3. \(\frac{1}{2}~\text{h}\)
4. \(1~\text{h}\)
When a man walks on a horizontal road with velocity \(1\) km/h, the rain appears to him coming vertically at a speed of \(2\) km/h. The actual speed of the rain with respect to ground is:
1. \(\sqrt{3}\) km/h
2. \(\sqrt{5}\) km/h
3. \(1\) km/h
4. \(3\) km/h
A man is crossing a river flowing with a velocity of \(5\) m/s. He reaches a point directly across the river at a distance of \(60\) m in \(5\) s. His velocity in still water should be:
1. \(12\) m/s
2. \(13\) m/s
3. \(5\) m/s
4. \(10\) m/s
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