Speed of light in air and glass are 3 × 10 8 m s - 1 and 2 × 10 8 m s - 1 , respectively. If a light ray travels 9 × 10 8 m in air and 16 × 10 8 m in glass, then what is the total time taken by it?

Speed of light in air, v 1 = 3 × 10 8 m s - 1 Distance travelled by light in air, s 1 = 9 × 10 8 m ∴ The time taken by light to travel in air, t 1 = s 1 v 1 t 1 = 9 × 10 8 m 3 × 10 8 m s - 1 = 3 s Speed of light in glass, v 2 = 2 × 10 8 m s - 1 Distance travelled by light in glass, s 2 = 16 × 10 8 m ∴ The time taken by light to travel in glass, t 2 = s 2 v 2 t 2 = 16 × 10 8 m 2 × 10 8 m s - 1 = 8 s ∴ The total time taken by light to travel = t = t 1 + t 2 = 3 s + 8 s = 11 s .

E M B I B E

Pearson IIT Foundation Physics>Chapter 2 - Kinematics>PRACTICE QUESTIONS (COMPETITION WING)>Q 79

EASY

7th CBSE

IMPORTANT

Earn 100

Can a body have a constant speed but a varying velocity?

Important Questions on Kinematics

MEDIUM

7th CBSE

IMPORTANT

Pearson IIT Foundation Physics>Chapter 2 - Kinematics>PRACTICE QUESTIONS (COMPETITION WING)>Q 80

A physics student observed a train of $100 m$ long crossing a bridge of length $245 m$ . If the train is moving with a velocity of $54 km h^{- 1}$ , he determines the time taken by it to cross the bridge. Find his answer.

HARD

7th CBSE

IMPORTANT

Pearson IIT Foundation Physics>Chapter 2 - Kinematics>PRACTICE QUESTIONS (COMPETITION WING)>Q 81

A body travels along a straight line for the first half of the total time with a constant speed of

20 m s^{- 1}

and for the second half of the total time with a constant speed of

30 m s^{- 1}

. Find the average speed of the body.

HARD

7th CBSE

IMPORTANT

Pearson IIT Foundation Physics>Chapter 2 - Kinematics>PRACTICE QUESTIONS (COMPETITION WING)>Q 82

Speed of light in air and glass are

3 \times 10^{8} m s^{- 1}

and

2 \times 10^{8} m s^{- 1}

, respectively. If a light ray travels

9 \times 10^{8} m

in air and

16 \times 10^{8} m

in glass, then what is the total time taken by it?

MEDIUM

7th CBSE

IMPORTANT

Pearson IIT Foundation Physics>Chapter 2 - Kinematics>PRACTICE QUESTIONS (COMPETITION WING)>Q 83

A body starts moving from a point A along the boundaries of a square field as shown in the figure and reaches the point C after $30 s$ . If its speed is $1 m s^{- 1}$ , what is the shortest distance between A and C?

Question Image

MEDIUM

7th CBSE

IMPORTANT

Pearson IIT Foundation Physics>Chapter 2 - Kinematics>PRACTICE QUESTIONS (COMPETITION WING)>Q 84

Ram and Raj travel along a straight line from X to Y with different uniform speeds. Ram started from X and reaches the place Y in $t s$ . If Raj travels half of the total distance between X and Y in $2 t s$ , determine the ratio of speeds of Ram and Raj.

MEDIUM

7th CBSE

IMPORTANT

Pearson IIT Foundation Physics>Chapter 2 - Kinematics>PRACTICE QUESTIONS (COMPETITION WING)>Q 85

A car moving along a straight road with a speed of