Important Questions Test: Motion & Time - Class 7 MCQ

• The distance-time graph of the non-uniform motion is a curved line as it covers unequal distances in equal intervals of time.

Non-uniform motion:

• Movement of an asteroid: Asteroids move in a non-uniform motion as they travel through space, changing speed and direction due to various gravitational forces acting on them.
• A car coming to a halt: When a car comes to a halt, it is an example of non-uniform motion as it starts with a certain speed and gradually slows down until it stops completely.
• A bouncing ball: A bouncing ball also exhibits non-uniform motion as it changes speed and direction each time it bounces off a surface.

Therefore, all of the given examples - movement of an asteroid, a car coming to a halt, and a bouncing ball - are examples of non-uniform motion as they involve changes in speed and direction over time.

If the scooter is travelling at precisely 30km/h in a perfectly straight line.
We know 1 hour=60 minutes
Therefore to calculate the distance traveled in the started fraction of the hour.

Therefore 10km is the distance traveled in 20 minutes of travelling at a speed of 30km/h

Given that,
Time t =2.5 min
⁡Distance d=2km

Now, firstly for half distance

Now, total time is
t = 150 - 90
t = 60s
Now, the speed is

Hence, the speed is 60 km/h

Given,
speed v = 150 km/h
distance cover = displacement   d=15 km    (Assume express is not changing its direction)

Time taken t = 0.1 hr

Explanation:

• Time of the first bell in the school: This expresses a specific time point when the bell rings in the school. It does not indicate a duration or interval.
• A day: This expresses a 24-hour time interval from one midnight to the next.
• A second: This expresses a very short time interval, equivalent to 1/60th of a minute.
• A school period: This expresses a specific duration of time during which classes are held in a school.

Therefore, option A: Time of the first bell in the school does not express a time interval as it refers to a specific point in time rather than a duration or period.

Odometer is an instrument used in the vehicle to measure the distance cover by it.

So, the car travels different distances in equal time intervals. This is an example of non-uniform motion.

- To find the speed of the car, we start with the distance traveled and the time taken.
- The car travels 15 km in 20 minutes.
- First, we convert time from minutes to hours: 20 minutes = 20/60 hours = 1/3 hours.
- Now, speed is calculated using the formula: Speed = Distance / Time.
- Substituting the values: Speed = 15 km / (1/3 hours) 

- Therefore, the correct answer is 45 km/h, which corresponds to option 3.