MCQ: Speed and Velocity - Class 9 MCQ

Speed can be calculated by the formula: speed = distance/time.

To find the unit of speed we need to know the units for distance and time first.

The standard unit (SI) for measurement of distance is meter (m) and time is second (s), so the unit of speed will be in meters per second (m/s).

Thus, the speed is measured in meters per second (m/s) in the SI system

Topic in NCERT: speed 

Line in NCERT: "The SI unit of speed is metre per second. This is represented by the symbol m s⁻¹ or m/s."

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

We use Speed = Distance / Time

Therefore, Distance = Speed × Time

Putting the values, we get:
Distance = 12 m/s × 25 min

Converting minutes into seconds, we get:
Distance = 12 m/s × 25 × 60 sec

Finally, we get:
Distance = 18,000 m

We can also write the distance in kilometers:
Distance = 18 km

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. 

Topic in NCERT: DISTANCE-TIME GRAPHS

Line in NCERT: "We can use the distance-time graph to determine the speed of an object."

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.

Topic in NCERT: Motion and Acceleration

Line in NCERT: error Occcured while getting response from embedding

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

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

=60 m/10 sec

=6m/s

Speed is the quantity which show only magnitude of the body whereas velocity is the quantity which shows the both magnitude and direction.

Topic in NCERT: SPEED WITH DIRECTION

Line in NCERT: "The quantity that specifies both these aspects is called velocity. Velocity is the speed of an object moving in a definite direction."

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.

Topic in NCERT: VELOCITY-TIME GRAPHS

Line in NCERT: "The height of its velocity-time graph will not change with time."

The area under the line in a velocity-time graph represents the distance travelled. To find the distance travelled in the graph above, you need to find the area of the light-blue triangle and the dark-blue rectangle. The width of the rectangle is 6 seconds and the height is 8 metres per second.

Topic in NCERT: VELOCITY-TIME GRAPHS

Line in NCERT: "The area under the velocity-time graph gives the distance (magnitude of displacement) moved by the car in a given interval of time."

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.

Topic in NCERT: VELOCITY-TIME GRAPHS

Line in NCERT: "The area under the velocity-time graph gives the distance (magnitude of displacement) moved by the car in a given interval of time."