Sections:

Motion in One Dimension, Page 7

Solved Problems

  • A man driving a truck with a velocity of 40 km/hr toward north takes 1.5 hour to reach the farm from home. What is the displacement of the truck when it reaches the farm? 

    Solution: 

    Given: velocity = 40 km/hr, time = 1.5 hr 

    Displacement =? 

    The displacement of the truck can be found out using the definition of velocity.

Velocity equals displacement divided by time; Displacement equals velocity multiplied by time; s equals 40 km/hr x 1.5 hr; s equals 60 km

  • A cockroach moves along the circular table of radius 60 cm. It takes 8 seconds to reach the diametrically opposite end. What is the speed of the insect? 

    Solution: 

    Given: radius = 60 cm, time = 8 seconds. 

    Speed =? 

    Speed is found using the formula below: 

    Speed = distance divided by time ---------- (1) 

    When the cockroach reaches the diametrically opposite end,

distance = pi x r; distance = 3.14 x 0.60 m; distance = 1.88 m

using the equation (1), we get,

 speed = 1.88 m / 8 s; speed = 0.235 m/s

  • A cockroach moves along the circular table of radius 60 cm. It takes 8 seconds to reach the diametrically opposite end. What is the velocity of the insect? 

    Solution: 

    Given: radius = 60 cm, time = 8 seconds. 

    Velocity =? 

    velocity = displacement / time ----------- (2) 

    When the cockroach reaches the diametrically opposite end, the displacement = 2 r 


Displacement = 2 x 0.60 m 

Displacement = 1.2 m 

Using the equation (2) we get, 

 velocity = 1.2 m / 8 s

velocity = 0.15 m/s