Grade 12Mechanics

A car has to cover the distance 60 km, if half of the total time it travels with velocity 80 km/h and in rest half time its speed becomes 40 km/h, the average speed of car will be,
(a) 60 km/h (b) 80 km/h
(c) 120 km/h (d) 180 km/h
How do we solve this question?

Kushi

11 Years agoGrade 12

2 Answers

Paarth Arkadi

11 Years ago

The problem can be solved by two methods

Method 1 :

V_av= 80 + 40 / 2

= 120/2

= 60 km /h

Method 2 :

Let the half time intervals be t

Therefore 60 = 80t + 40t

t=1/2

total time = 1/2*2 = 1hr

v_av= Total distance / Total time

= 60 / 1

= 60 km/h

Agam Dogra

11 Years ago

Question can be asked in two ways;

1)when paritcle travel with speed v₁in time t/2 and speed v₂ in time t/2 then V_av=v₁+v₂/2 (when time interval is equal).

2)when paritcle travel with speed v₁for distance x and speed v₂ distance x then V_av =2v₁v₂/v₁+v₂(when distance covered is equal).

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A car has to cover the distance 60 km, if half of the total time it travels with velocity 80 km/h and in rest half time its speed becomes 40 km/h, the average speed of car will be,(a) 60 km/h (b) 80 km/h(c) 120 km/h (d) 180 km/hHow do we solve this question?

Kushi

2 Answers

Paarth Arkadi

Agam Dogra

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A car has to cover the distance 60 km, if half of the total time it travels with velocity 80 km/h and in rest half time its speed becomes 40 km/h, the average speed of car will be,
(a) 60 km/h (b) 80 km/h
(c) 120 km/h (d) 180 km/h
How do we solve this question?

A car loaded with water having total mass 1000 kg moves on a straight horizontal Road starting from rest under the action of a force of 100 Newton. The water spills throw a small hole in the bottom at a rate of 0.1 KG per second the velocity of cart after 300 seconds is nearly.

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