Question

A 1391.3 kg car is traveling at 29.8 m/s when the driver takes his foot off the gas pedal. It takes 4.9 s for the car to slow down to 20 m/s. How large is the net force slowing the car

Answer 1

Fnet = 2782.6 N

Step-by-step explanation:

• Newton's 2nd Law states that the net force applied to an object, is equal to its mass times the acceleration.
• By definition, acceleration is the rate of change of velocity with respect to time, as follows:

`a = (\Delta v)/(\Delta t)`

where Δv = vf - v₀ and Δt = tfi - t₀, replacing by the givens:

`\Delta v = v_(f) - v_(o) = 20 m/s - 29.8 m/s = -9.8 m/s`

Δt = 4.9 s

⇒
`a = (-9.8m/s)/(4.9s) = -2 m/s2`

• We can now apply Newton's 2nd Law, solving for Fnet, as follows:

`F_(net) = m* a = 1391.1 kg * (-2 m/s2) = -2782.6 N`

• The magnitude of the is net force (How large it is ) is just:
• Fnet = 2782.6 N