Chapter 13 : Motion and Time- Fill in the Blanks with Answers and Explanations (Solved Worksheet)
1. The distance covered by an object in a unit of time is called its __________.
Answer: Speed
Explanation: Speed is defined as the distance an object travels over a unit of time. It is a measure of how quickly an object is moving.
2,The SI unit for measuring speed is __________ per second.
Answer: metres
Explanation: The standard International System of Units (SI) for speed is metres per second (m/s), which measures how many metres an object travels in one second.
3,In a __________ motion, the speed of an object changes over time.
Answer: Non-uniform
Explanation: Non-uniform motion occurs when an object’s speed is not constant throughout its journey, meaning the object accelerates or decelerates.
4.A simple __________ consists of a weight suspended from a fixed point so it can swing freely.
Answer: pendulum
Explanation: A simple pendulum is a device that consists of a heavy object, known as a bob, attached to a fixed point by a string or rod, which can swing back and forth under the influence of gravity.
5.The time taken for one complete oscillation of a pendulum is called the __________ period.
Answer: time
Explanation: The time period of a pendulum is the duration it takes to complete one full swing from one side to the other and back.
6.A car moving with a uniform speed will have a __________ line in a distance-time graph.
Answer: straight
Explanation: In a distance-time graph, uniform motion, where the object moves at a constant speed, is represented by a straight line.
7.A pendulum used for timekeeping must have a __________ time period.
Answer: constant
Explanation: A pendulum for timekeeping must have a constant time period, meaning the duration of each oscillation remains the same, ensuring accurate time measurement.
8.When measuring large distances such as between cities, the preferred unit is __________.
Answer: kilometres
Explanation: Kilometres are used to measure larger distances because they provide a more convenient and practical scale for such measurements than metres, which can result in unwieldy large numbers.
9.A car parked on a side road will have a horizontal line in its distance-time graph, indicating a speed of __________.
Answer: zero
Explanation: A horizontal line on a distance-time graph indicates that the distance remains constant over time, which means the object is not moving, hence a speed of zero.
10.If a vehicle covers a distance of 150 kilometres in 3 hours, its speed is __________ km/h.
Answer: 50
Explanation: The speed of the vehicle is calculated by dividing the distance by the time. Therefore,
150 km/ 3 h=50 km/h
11.When converting from km/h to m/s, we multiply the speed by __________.
Answer :⅓.6
Explanation: To convert km/h to m/s, we multiply by ⅓.6
(or equivalently, divide by 3.6) because there are 3.6 kilometres in a metre.
12.The __________ is the basic unit of time in the International System of Units.
Answer: second
Explanation: The second is the SI base unit for time. It is widely used in science and everyday life as the standard unit for measuring time intervals.
13.__________ is the motion of a child on a see-saw.
Answer: Oscillatory
Explanation: A child on a see-saw moves back and forth around a central point, which is a type of periodic motion known as oscillatory motion.
14.A car’s __________ is a device that measures the instantaneous speed of the vehicle.
Answer: speedometer
Explanation: The speedometer is an instrument in a vehicle that displays the current speed at which the vehicle is moving at any given moment.
15.The __________ of a clock measures the distance travelled by the car.
Answer: odometer
Explanation: The odometer is a device in a vehicle that records the total distance that the vehicle has travelled.
16.If a bicycle has a speed of 2 m/s, in 60 seconds, it will cover a distance of __________ metres.
Answer: 120
Explanation: Distance is calculated by multiplying speed with time. Thus, a bicycle moving at 2 m/s will cover
2 m/s×60 s=120 metres
17.The speed of an object is the distance travelled divided by the __________ taken to cover that distance.
Answer: time
Explanation: Speed is defined as the distance travelled per unit of time. The formula for speed is
speed=distance / time
18.An object that moves back and forth in a regular rhythm is undergoing __________.
Answer: oscillation
Explanation: Oscillation refers to the movement of an object back and forth from its rest position in a regular pattern.
19.The graph that represents the motion of an object in a pictorial form is called a __________-time graph.
Answer: distance
Explanation: A distance-time graph is a graphical representation of how the distance travelled by an object changes over time.
20.The graph for an object that is not moving is a __________ line parallel to the time axis.
Answer: horizontal
Explanation: If an object is not moving, the distance does not change over time, so the distance-time graph shows a horizontal line indicating no change in distance as time progresses.
21.The time taken by the Earth to complete one revolution around the Sun is called a __________.
Answer: year
Explanation: A year is defined as the time it takes for the Earth to orbit the Sun once, which is about 365.25 days.
22.A device used to measure the distance travelled by a vehicle is known as an __________.
Answer: odometer
Explanation: An odometer is an instrument typically found in vehicles that records the total distance they have travelled.
A motion where the object covers equal distances in equal intervals of time is called 23.__________ motion.
Answer: uniform
Explanation: Uniform motion is characterised by an object moving at a constant speed, covering equal distances in equal time intervals.
24.Speed can also be expressed in __________ per hour (km/h).
Answer: kilometres
Explanation: The speed of an object can be expressed in kilometres per hour, which denotes how many kilometres the object travels in one hour.
25.The shape of the distance-time graph for non-uniform motion is usually a __________ line.
Answer: curved
Explanation: In a distance-time graph, non-uniform motion is depicted by a curved line, indicating that the speed is changing over time.
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