Free Motion and Time 01 Practice Test - 7th grade 

Question 1

An object is observed from two points A and B. The object changes its position continuously with respect to A. However, the position of the object is constant with respect to B. Which of the following is/are true?

A.

The object is in motion with respect to B.

B.

The object is in motion with respect to A.

C.

The object is at rest with respect to B.

D.

The object is at rest with respect to A.

SOLUTION

Solution : B and C

An object is said to be in motion when its position changes with respect to the reference point.
In this situation, there are two reference points, A and B. From the point of view of A, the object is changing its position. Hence, it's said to be in motion with respect to A. 
From the point of view of B, the object is not changing its position. Hence, it's said to be at rest with respect to B.

Question 2

In order to cover a certain distance in a shorter time span, the object should have a greater _________.

A.

mass 

B.

speed

C.

time period 

D.

frequency

SOLUTION

Solution : B

We know that:
Speed=DistanceTime
Here, the object has to cover a certain fixed distance in a shorter span of time.
From the equation above, we understand that greater the speed, lesser is the time taken, provided the distance is constant.
So, in order to cover a certain distance in a shorter time span, the object should have a greater speed.

Question 3

The odometer of a vehicle has an initial reading of 22256 km. After the trip, it shows a reading of 22356 km. If the time taken for the trip is 5 hours, what is the average speed of the vehicle?

A. 20 km h−1
B. 30 km h−1
C. 40 km h−1
D. 50 km h−1

SOLUTION

Solution : A

Given:
Odometer reading, before the trip =22256 km.
Odometer reading, after the trip =22356 km.
So the distance travelled in the trip=22356−22256=100 km.
Time taken for the trip =5 h.
Average speed = Total distance travelledTotal time taken
∴Average speed =1005=20 km h−1.

Question 4

If the speed of a moving object is 5 kmph then, how much distance will it cover in 10 hours?

A. 50 km
B. 60 km
C. 40 km
D. 25 km

SOLUTION

Solution : A

Given, 
Speed =5 kmph and Time =10 h
We know that:
Distance = Speed × Time
⇒Distance =5×10=50 km.

Question 5

The distance-time graph for a uniform motion is a ____.

A.

straight line parallel to X-axis

B.

straight line parallel to Y-axis

C.

straight line having 450 to X-axis

D. curved line

SOLUTION

Solution : C

In uniform motion, a body covers an equal distance in equal interval of time.
Hence, the ratio Change in distanceChange in time is constant. When we plot the graph with distance on the Y-axis and time on the X-axis, we see that the points lie along a straight line inclined at 450 with the x-axis.

Question 6

Which among the following is the unit of distance?

A. Metres
B. Kilometres
C. Hours
D. Kilograms

SOLUTION

Solution : A and B

A distance is usually described using the physical quantity 'length'. Hence, the unit of distance is the same as unit of length, which is a fundamental quantity.
Here, metres and kilometres are units of length. Hours is a unit of time and kilograms is a unit of mass.

Question 7

The motion of a simple pendulum is an example of:

A. Oscillatory motion
B. Circular motion
C. Rotational motion
D. Rectilinear motion

SOLUTION

Solution : A

Oscillatory motion is the type of motion in which an object moves to and fro about a fixed point. The swinging of a pendulum is an example of oscillatory motion.
 

Question 8

Sundial is a device that measures _____.

A. distance
B. temperature
C. volume
D. time

SOLUTION

Solution : D

Sundial is a time measuring device. It shows the time by the shadow of a pointer cast by the sun onto a plate marked with the hours of the day.

Question 9

Identify the device that is used to measure how fast a vehicle is moving.

A. Sundial
B. Thermometer
C. Speedometer
D. Odometer

SOLUTION

Solution : C

Speed is a quantity that defines how fast an object or a vehicle is moving.
A speedometer is a device which is used to measure the speed of a vehicle. It records the speed in kmph.

Question 10

Match the entries of column I with column II.

Activity Type of Motion
(a) Movement of the tip of the minute hand of a clock (i) Rotational motion
(b) A stone falling from a height in a straight line path (ii) Circular motion
(c) Moving wheel of a sewing machine (iii) Linear motion
A. (a) - (iii), (b) - (i), (c) - (ii)
B. (a) - (ii), (b) - (iii), (c) - (i)
C. (a) - (iii), (b) - (ii), (c) - (i)
D. (a) - (ii), (b) - (i), (c) - (iii)

SOLUTION

Solution : B

  1. When a body moves in a circular path with respect to time, it is known as circular motion. e.g. the tip of minute hand.
  2. When a body moves in a straight line with respect to time, it is known as linear motion. e.g the stone falling from a height.
  3. When a body moves about its own axis, it is known as rotational motion. e.g. the wheel of the sewing machine.
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