MCQ: Speed and Velocity - Class 9 MCQ

When the automobile moves at 12 m/s for 25 minutes, we must calculate the distance.

Hence the car will travel 18 km in 25 min at 12 m/s.

Average Velocity Calculation

- Average velocity is calculated by dividing the total distance traveled by the total time taken to travel that distance.
- In this case, the car moved 60 km in 3 hours.
- Therefore, the average velocity is calculated as 60 km / 3 hours = 20 km/h.

Therefore, the average velocity of the car is 20 km/h. So, the correct answer is B: 20 km/h.

We can use Steepness, or slope, of a line in a distance - time  graph  to determine the speed of an object if speed is constant. The slope of the line is calculated by dividing the change in distance by the change in time for that time interval. 

Conversion of km/h to m/s

1 km = 1000 m and 1 hour = 3600 s

• 1 km/h is equal to 1000 m/3600 s
• Therefore, 1 km/h = 5/18 m/s
• So, the correct answer is D: 5/18

Taking the formula when both bodies are moving along opposite direction we have :

V(AB) =  V(A) -  V(B)  =  40 - (-10 ) = 50 km/hr

Hence the velocity of car A with respect to car B is 50 km/hr in opposite direction.

Velocity is a vector quantity, which means it has both magnitude and direction. To correctly measure and describe velocity, you need both these components.

Here’s the analysis of the provided options:

1. 30 s: This is a measure of time, not velocity.

2. 30 m/s: This is a measure of speed, not velocity, because it does not include a direction.

3. 30 South: This describes a direction but lacks the magnitude (speed), so it is not a complete measure of velocity.

4. 30 m/s, South: This provides both magnitude (30 m/s) and direction (South), making it a complete measure of velocity.

So, the correct measure of velocity is:

4. 30 m/s, South

Calculating Distance Traveled:

Speed = 2 m/s

Time = 12 s

[Distance = Speed x Time]

Therefore, Distance = 2 m/s x 12 s = 24 meters

The instantaneous speed of an object is defined as the speed of the object at any given instant. The instantaneous speed of an object can be determined by determining the average speed over a short distance (and short time), and using this approximation as the instantaneous speed.

Average speed= (Total Distance)/(Total time)

= (20 m + 40 m)/(5 sec + 5 sec)

=60 m/10 sec

=6m/s

Scalar quantities have only magnitude and no direction. Speed is the scalar quantity here. Therefore, the correct answer is: D) Speed

Average Speed Calculation

• Average speed is calculated by dividing the total distance traveled by the total time taken.

• In this case, the car travels 240 km in 4 hours.

• Therefore, the average speed = Total distance / Total time = 240 km / 4 hours = 60 km/h.

• So, the correct answer is B: 60 km/h.

The speed-time graph for a particle moving at constant speed is a straight-line parallel to the time axis.

Calculation of Average Speed

- Step 1: Calculate the total distance traveled
- Anjali travels 15 km + 25 km = 40 km in total.

- Step 2: Calculate the total time taken
- Time taken to travel the first 15 km = 15 km / 30 km/h = 0.5 hours
- Time taken to travel the next 25 km = 25 km / 10 km/h = 2.5 hours
- Total time taken = 0.5 hours + 2.5 hours = 3 hours

- Step 3: Calculate the average speed
- Average speed = Total distance / Total time taken
- Average speed = 40 km / 3 hours = 40/3 km/h

Therefore, Anjali's average speed for the entire journey is 40/3 km/h. So, the correct answer is A: 40/3 km/h.

Calculating the Time Taken to Reach Destination

- Given:
- Distance traveled: 60 km
- Speed of the car: 30 km/h

- Formula:
- Time = Distance / Speed

- Calculation:
- Time = 60 km / 30 km/h
- Time = 2 hours

Therefore, it will take 2 hours for the car to reach its destination. So, the correct answer is option A: 2 hours.

The speedometer device is used to measure speed. A speedometer is also called a speedometer, it is a gauge that measures and displays the instantaneous speed of a vehicle.

Area under the speed-time graph gives the distance:

• When calculating the area under a speed-time graph, you are essentially finding the total distance traveled by an object over a certain period of time.
• This is because the area under a speed-time graph represents the total distance covered by an object as it moves at varying speeds.
• By finding the area under the curve on a speed-time graph, you can determine the total distance traveled by the object during that time interval.