Science Worksheet (Set 7)
Topic: Motion and Time
Grade: VII
Q1. Answer briefly:
a. Which of the following is the most suitable device for measuring the time taken in a 100m marathon?
- Hour glass
- Stop watch ✅
- Pendulum
- Sun Dial
A stopwatch is the most suitable device because it provides precise time measurement in seconds and fractions of a second.
b. Write two factors that affect the period of a simple pendulum.
1. The length of the pendulum.
2. The acceleration due to gravity.
2. The acceleration due to gravity.
c. What will be the motion of a ball tied to a string being swung in a circle?
Circular motion.
d. How is the distance & speed covered by a vehicle indicated?
Distance is indicated by the odometer, and speed is indicated by the speedometer.
e. Complete the given information:
– A pendulum is a simple system that moves back and forth around a fixed point.
– The maximum distance it swings from the resting position is called its amplitude.
– The time it takes for the pendulum to complete one full swing, from one extreme to the other and back, is called the time period.
– If a pendulum swings many times in one second, it has a higher frequency.
– The relationship between the time period and frequency is that they are inversely related, meaning that as the time period increases, the frequency decreases.
– The maximum distance it swings from the resting position is called its amplitude.
– The time it takes for the pendulum to complete one full swing, from one extreme to the other and back, is called the time period.
– If a pendulum swings many times in one second, it has a higher frequency.
– The relationship between the time period and frequency is that they are inversely related, meaning that as the time period increases, the frequency decreases.
f. What happens when metals are cooled down?
Metals contract (shrink) when cooled due to the decrease in kinetic energy of their particles.
g. The principle of __________ was developed based on Galileo Galilei’s discovery of the pendulum principle.
Timekeeping in clocks
Q2. Answer the following questions:
a. Swapna traveled by plane flying at an average speed of 600 Km/h. The plane left the airport at 13:00h and reached the destination at 15:45h. How far did Swapna travel?
– Time taken = (15:45 – 13:00) = 2.75 hours
– Distance = Speed × Time
\[ 600 × 2.75 = 1650 \] km
– Distance = Speed × Time
\[ 600 × 2.75 = 1650 \] km
Swapna traveled 1650 km.
b. A pendulum completes 10 oscillations in 20 seconds, while a vibrating guitar string completes 500 vibrations in the same time.
i. Which motion is slower?
The pendulum motion is slower because it completes fewer oscillations in the same time compared to the vibrating guitar string.
ii. How do the number of oscillations or vibrations affect our perception of speed?
Higher oscillation or vibration frequencies give a sense of faster movement, whereas slower oscillations appear as slow motion.