A 950 kg automobile is at rest at a traffic signal. At the instant the light turns green, the automobile starts to move with a constant acceleration of 2.6 m/s2. At the same instant a 1950 kg truck, traveling at a constant speed of 6.8 m/s, overtakes and passes the automobile.
a. How far is the center of mass of the automobile-truck system from the traffic light at t = 3.0 s?
b. What is the speed of the com then?

(a)

(b)

Explanation:

Given data

950 kg automobile starts from rest with constant acceleration  2.6m/s²

1950 kg truck, traveling at a constant speed of 6.8 m/s

Automobile position

Velocity

Truck Position

Velocity of truck remain constant vt=6.8m/s

For Part (a)

The center of mass for Automobile Truck system:

For Part (b)

The velocity of center of mass for Automobile Truck system:

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