An object has a kinetic energy of 249 j and a momentum of magnitude 24.6 kg · m/s.(a) find the speed of the object.

The speed of the object is 20.24 m/s.  

Explanation:

For a body of mass 'm' travelling with velocity 'v' , its kinetic energy is gievn by -

--- 1

The momentum of body is given by -

---- 2

Dividing equation 1 and 2 , we get -

Given that ,

KE = 249 J

p   = 24.6 kg.m/s

Substituting the 2 values in the above equation , we get -

v = 20.24 m/s.

0.96 kWh

Explanation:

First of all, we can find the power of the appliance using the formula:

where

V = 120 V is the voltage of the source

I = 2 A is the current

Substituting,

Now we want to find the amount of energy used by the applied in a time of

t = 4 h

The amount of energy is given by

where

P = 0.24 kW

t = 4 g

Substituting,