Question

The sports car has a mass of 1500 kg and a center of mass at G. Determine the shortest time it takes for it to reach a speed of 20 m/s, starting from rest, if the engine only drives the rear wheels, whereas the front wheels are free rolling. The coefficient of friction between the wheels and road is μ 0.2. Neglect the mass of the wheels for the calculation 0.35m 0,33m ZTUrt22.27 g-ru, al. iat 4 k's /ldi suk. 1.25m0.75m (1500)(9.81)N A. t- 22.7 B. t 19.8 s C. t 15.7 s D. t 14.1 s 0.35m o.2Np 125向"や75m

Answer 1

In the given problem, we need to compute the shortest time that car takes to reach a speed of 20 m/s starting from 0 m/s.

Condition is that, the engine of the car only drives the rear wheels. The complete step by step procedure for solution is provided below.

Answer : t = 15.7 s

SoluHon ruen that mass of caoy , m-1500 Kg CoEfficient of Foriction betueen whe els and oad 1500 (9-81) a. 35m S5ba No NA 0.15m 1.25 shountest time to take for the Ca to steach a speed of 20 mls m/s 20 Ulven, speed,

-component forces ct → y-component 031 direction fo ces, - ay → Taking mo ments about U, ci.. Condition gien s that, engine only drives the Stear wheels Then, the sicHonal force in front 0 wheels, FA-O-2xdA

Fsom equation o02N500 (iii), Foom equation Na C135) o (o 1s)-.oaN- -wn (1.25) + NB (0.15-0.07) :0 -Nn (1.25) + 0.68 NB = o Fston equation Substitute equation u in equation w) we get 15 x(5).GSNG 18,393.75 NB (h25to. 6 8 ) -) N 8,393 15 9 530, 44

5304 = 9.53 KN Ftomeq,uation tui 1500x9-81-9530-44 5184 56 nla S.IS KN From equaHonCtv) 0.2 (9530.44) 1500 a 02 x 9530 44 50D sing eq,ua on of mohon 20O 2 Ct) speed t-20-15-7s 1-2チ!

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