1D Kinematics 1. A ball rolling down a hill was displaced 19.6 m while uniformly

Question

1D Kinematics 1. A ball rolling down a hill was displaced 19.6 m while uniformly accelerating from rest. If the final velocity was 5.00 m/s, what was the rate of acceleration? 2. If a bullet leaves the muzzle of a rifle at 600.0 m/s, and the barrel is 0,90 m long, what was the acceleration of the bullet while in the barrel? 3. A driver of a car going 90 km/h suddenly sees the lights of a barrier 40.0 m ahead. It takes the driver 0.75 s before he applies the brakes. Once he does begin to brake, he decelerates at a rate of 10.0 m/s a. Does he hit the barrier? What would be the maximum speed at which the car could travel and NOT hit the barrier 40.0 m ahead? b.

Explanation / Answer

1. displacement, s =19.6 m

final velocity, v = 5 m/s

initial velocity u = 0m/s

acceleration = a = constant

2*a*s = v^2 - u^2

2*a*19.6 = 25

a = 0.6377 m/s/s

2. muzzle velocity, v= 600 m/s

length of barrel, l = 0.9 m

acceleration = a = constant

2*a*l = v^2 - u^2

2*a*0.9 = 600^2

a = 200000 m/s/s

3. speed of driver, u = 90 km/hr = 25 m/s

distance from barrier, d = 40 m

time taken to apply brakes, t = 0.75 s

deceleration a= 10 m/s/s

a. total distance travelled before stoppin = t*u + u^2/2*a

distance = 0.75*25 + 25^2/2*10 = 50 m

so the man does hit the barrier

b. let this maxiumu speed be u

40 = u*0.75 + u^2/20

u^2 + 15u - 800 = 0

solveing for u

u = 21.76 m/s = 78.336 km/hr

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

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