A5.0-kg box rests on a horizontal surface. the coefficient of kinetic friction between the box and surface is =0.50. a horizontal force pulls the box at constant velocity for 10 cm. find the work done by (a) the applied horizontal force, (b) the frictional force, and (c) the net force.

a)W= 1 J

b)W= 1 J

c)W= 0 J

Explanation:

Given that

m = 5 kg

Coefficient of kinetic friction,K=0.5

d= 10 cm

We know that if velocity is constant it means that the acceleration of the system is zero.Or we can say that all forces are balance in the system.

We know that work is the dot product of force and displacement

W= F.d

The friction force on the box

Fr= K m g

Fr= 0.5 x 5 x 10 = 25 N                      ( take g =10 m/s²)

Fr=25 N

a)

Acceleration a= 0

So horizontal force F = Fr

W = Fr.d

W=10 x 0.1 J

W= 1 J

b)

The work done by friction force

W= 1 J

c)

The net force on the system is zero because acceleration is zero.

F= 0

So

W= 0 J

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27

the answer is false. this is because for ice to melt, it requires latent heat of melting. latent heat means heat energy required to change phase without any increase in temperatures. therefore, the ice will take energy from the environment to melt hence atmospheric temperatures will reduce.