1. A car with mass m=1500 kg has a motor that can exert a force Fe =2800 N on it

Question

1. A car with mass m=1500 kg has a motor that can exert a force Fe =2800 N on it. With the car initially at rest, the motor is engaged at full throttle. You can neglect the drag force from air in this problem.

(a) Calculate the speed of the car after t=20 s.

(b) Calculate how far the car moves during those first t=20 s.

2. A Rotor in an amusement park spins customers in a horizontal plane until they are pinned to the walls. Above a certain angular velocity the floor drops out leaving static friction between the customers and the walls of the rotor to keep them from falling down. The static coefficient of friction between the wall and the most slippery customer is µs=0.2 and the radius of the rotor is R=6 m. (a) Calculate the minimum angular speed required to avoid loss of customers when the floor drops.

Explanation / Answer

here,

mass of the car , m = 1500 kg

force exerted , Fe = 2800 N

the accelration , a = Fe/m

a = 2800/1500

a = 1.87 m/s^2

(a)

time taken , t = 20 s

let the velocity be v

using first equation of motion

v = u + a*t

v = 0 + 1.87 *20

v = 37.33 m/s

the velocity of the car after 20 s is 37.33 m/s

(b)

let the distance travelled by the car be d

using seccond equation of motion

d = u*t + 0.5 * a * t^2

d = 0 + 0.5 * 1.87 *20^2

d = 374 m

the distance ytravelled in 20s is 374 m

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