The velocity of a 640-kg auto is changed from 10.0 m/s to 44.0 m/s in 71.0 s by an external, constant force. (a) what is the resulting change in momentum of the car? kg · m/s (b) what is the magnitude of the force? n

(a) change in momentum of the car = 21760 kgm/s

(b) The magnitude of the force = 306.48 N

Explanation:

(a)

Change in momentum: This is the product of mass and change in velocity. The unit of momentum is kgm/s. It can be expressed mathematically as,

Change in momentum of the car = m(v-u) Equation 1

Where m = mass of the car, v = final velocity of the car, u = initial velocity of the car.

Given: m = 640 kg, v = 44.0 m/s, u = 10.0 m/s.

Substituting these values into equation 1,

Change in momentum of the car = 640 (44-10)

change in momentum of the car = 640× 34

change in momentum of the car = 21760 kgm/s

change in momentum of the car = 21760 kgm/s

(b) Force: Force of a body can be defined as the product of mass and its acceleration. It is measured in Newton (N). It can be expressed mathematically as,

Force = ma Equation 2

   Or

Force = m(v-u)/t Equation 3

Where m = mass of the car, v = final velocity of the car, u = initial velocity of the car, a = acceleration of the car, t = time taken to change the velocity.

Given: m = 640 kg, u = 10.0 m/s v = 44 m/s, t = 71 s.

Substituting these values into equation 3

Force = 640(44-10)/71

Force = (640×34)/71

Force = 306.48 N

The magnitude of the force = 306.48 N

Answer : The voltage of flat screen television is 100 V.

Explanation :

It is given that,

Current used by a flat screen television,

Power rating,

We have to find the amount of voltage used by television.

Power of an electrical equipment is given by :

or

So, the correct option is (B) "100 V"

Hence, this is the required solution.