Solve the following problems: 1. A car traveling 85 Km/hr slows down at a consta

Question

Solve the following problems: 1. A car traveling 85 Km/hr slows down at a constant 0.50 m/sec just be "letting up on the gas." Calculate (a) the distance the car coasts before it stops, (b) the time it takes to stop, and (c) the distance it travels during the first second. 2. A tiger leaps horizontally from 7.5 m high rock with speed of 3.2 m/sec. How far from the base of the rock will the tiger land? A particle is moving with acceleration given by alt)- 3t Given V-48 ft/sec when t -4 sec and V- -16ft/sec when t 0 sec (A) find the Velocity, V as a function of time and (B) the position X as a function of time knowing that X-0 when t-4 sec 3.

Explanation / Answer

1.

given

u = 85 km/hr = 85*5/18 =23.61 m/s

a = 0.50 m/s2

v = 0 m/s

(a)

v2 = u2 +2as

0 = (23.61)2 - 2*0.50*s ( a is decceleration . )

s =  557.43 m

(b)

so, v = u+at

0 = 23.61 - 0.50 *t

t = 47.22 s

(c)

s = u*t + 1/2*a*t2

s = 23.61*1 + 1/2*0.5*1

s = 23.86 m

2.

Calculating time it takes for her to land is based on

D= V (initial)*t + 1/2*a*t2

7.5 = 0 * t + 0.5*9.8* t2    (In terms of vertical motion, the tiger started from rest, so initial velocity = 0)

t = 1.23 sec

Since time airbourne = 1.23 s,

distance which the tiger went horizontally from the rock is d = v * t = 3.2*1.23 = 3.95 m  

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