A car that weighs 1.2 × 10 4 N is initially movingat a speed of 44 km/h when the

Question

A car that weighs 1.2 × 104 N is initially movingat a speed of 44 km/h when the brakes are applied and the car isbrought to a stop in 16 m. Assuming that the force that stops thecar is constant, find (a) the magnitude of thatforce and (b) the time required for the change inspeed. If the initial speed is doubled, and the car experiences thesame force during the braking, by what factors are(c) the stopping distance and (d)the stopping time multiplied? (There could be a lesson here aboutthe danger of driving at high speeds.)

Answer a1: the tolerance is +/-2%
Answer b1: the tolerance is +/-2%
Answer c1: the tolerance is +/-2%
Answer d1: the tolerance is +/-2%

Pls include correct units and be clearwith your answers...

Explanation / Answer

first,   44 km/h is    12.222 m/s      and    12000 N is massof     1224.5 kg . Then... . (a)   findacceleration:     a = v2/ 2d = 12.2222 / 2 * 16 =    4.6682 .            Force = ma =   1224.5 * 4.6682 =    5716 Newtons . (b)     time = speed /acc = 12.222 / 4.6682 =     2.618 second. . (c) Now speed is multiplied by 2. Andacceleration is the same. We can see that... .                        d = v2 /2a          so if v isdoubled, distance ismultiplied by a factor of 4. .   (d)    Since     time = v /a           if v is doubled, then the time doubles, i.e. multipled by a factor of 2.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.