Calculate the average force a bumper would have to exert to bring a 1200-kg car to rest in 15 cm when the car had an initial speed of 2.0 m/s (about 4.5 mph)

-16000 N

Explanation:

Force: This can be defined as the product of mass of a body and its acceleration. The S.I unit of force is Newton (N). The formula of force is given as

F = ma Equation 1

Where F = Force, m = mass of the car, a = acceleration of the car.

But,

v² = u²+ 2as Equation 2

Where v = final velocity, u = initial velocity, a = acceleration, s = distance.

make a the subject of the equation.

a = (v²-u²)/2s Equation 3

Given: v = 0 m/s², ( brought to rest), u = 2 m/s, s = 15 cm = 0.15 m.

Substitute into equation 3

a = (0²-2²)/(2×0.15)

a = -4/0.3

a = - 13.33 m/s²

Also given: m = 1200 kg.

substitute into equation 1

F = 1200(-13.33)

F = -16000 N

since you're a real machine, your ama is always less than your ima, because you can never totally eliminate friction.

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