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Tuba

Jun 13, 2014



Rk sharma

Mar 6, 2015

#### A body cools from 80 °C to 50 °C in 5 minutes.  Calculate the time it takes to cool from 60°C to 30 °C.  The temprature of the surroundings is 20°C.



According to Newton's law of cooling, we have

mc (T1 - T2)/t = k [(T1 + T2)/2   -  T0)]        -----------...

Amarnathreddy M

Feb 3, 2014

#### A ball is dropped from rest at a height of 12 m. If it loses 25% of its kinetic energy on striking the ground, what is the height to which it bounces? How do your account for the loss in kinetic energy?



Solution:
Given a ball is at a height (h) of 12m
When a body at certain height poses maximum potential energy which converted into kinetic energy when a  ball just before...

Sanalkumar S

Mar 10, 2015

#### A car of mass 1000 kg moving with velocity of 30 m/s collides with the back of a stationry lorry of mass 9000 kg. Calculate the speed of vehicle immediatly after the collision if they remain jammed together.



Given:
Mass of the car (m1)= 1000 kg
Initial velocity of the car (u1 )= 30 m/s
Mass of the lorry (m2)= 9000 kg
Initial...

Dinesh

Jan 16, 2015

#### The work done by a spring force : (1) is always negative (2) is always positiv..



Spring force F = − kx (Hooke's law)

The minus sign indicates that the spring force is always opposite in direct...

Navaneeth K

Oct 19, 2014

#### CAN anyone answer Question 6.15 in NCERT text book. i cannot understand the method of solution used in learnnext solved exercise. A pump on the ground floor of a building can pump up water to fill a tank of volume 30m cube in 15 minutes.if the tank is 40 m above the ground,and efficiency of pump is 30%,how much electric power is consumed by the pump?



Volume of water = 30 m3.

Tuba

Feb 6, 2015



Dinesh

Jan 16, 2015

#### Two bodies having masses m1 and m2 and velocities u1 and u2 collide and form a composite system. If m1+ m2= 0 (m1≠ m2), th..



Given:  m1u+  m2u = 0
Initial momentum = Final momentum
⇒ m1u

Amarnathreddy M

Feb 3, 2014



Sanalkumar S

Mar 17, 2015

#### Why the work done by centripetal force is zero?



We know that
Work, W = F. S Cos θ.

As the centripetal force is perpendicular to the dispalcement   = 90 0

⇒

Tuba

Jun 13, 2014



Rk sharma

Mar 6, 2015

#### A body cools from 80 °C to 50 °C in 5 minutes.  Calculate the time it takes to cool from 60°C to 30 °C.  The temprature of the surroundings is 20°C.



According to Newton's law of cooling, we have

mc (T1 - T2)/t = k [(T1 + T2)/2   -  T0)]        -----------...

Amarnathreddy M

Feb 3, 2014

#### A ball is dropped from rest at a height of 12 m. If it loses 25% of its kinetic energy on striking the ground, what is the height to which it bounces? How do your account for the loss in kinetic energy?



Solution:
Given a ball is at a height (h) of 12m
When a body at certain height poses maximum potential energy which converted into kinetic energy when a  ball just before...

Sanalkumar S

Mar 10, 2015

#### A car of mass 1000 kg moving with velocity of 30 m/s collides with the back of a stationry lorry of mass 9000 kg. Calculate the speed of vehicle immediatly after the collision if they remain jammed together.



Given:
Mass of the car (m1)= 1000 kg
Initial velocity of the car (u1 )= 30 m/s
Mass of the lorry (m2)= 9000 kg
Initial...

Dinesh

Jan 16, 2015

#### The work done by a spring force : (1) is always negative (2) is always positiv..



Spring force F = − kx (Hooke's law)

The minus sign indicates that the spring force is always opposite in direct...

Navaneeth K

Oct 19, 2014

#### CAN anyone answer Question 6.15 in NCERT text book. i cannot understand the method of solution used in learnnext solved exercise. A pump on the ground floor of a building can pump up water to fill a tank of volume 30m cube in 15 minutes.if the tank is 40 m above the ground,and efficiency of pump is 30%,how much electric power is consumed by the pump?



Volume of water = 30 m3.

Tuba

Feb 6, 2015



Dinesh

Jan 16, 2015

#### Two bodies having masses m1 and m2 and velocities u1 and u2 collide and form a composite system. If m1+ m2= 0 (m1≠ m2), th..



Given:  m1u+  m2u = 0
Initial momentum = Final momentum
⇒ m1u

Amarnathreddy M

Feb 3, 2014



Sanalkumar S

Mar 17, 2015

#### Why the work done by centripetal force is zero?



We know that
Work, W = F. S Cos θ.

As the centripetal force is perpendicular to the dispalcement   = 90 0

⇒

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