Question

Each of the following automobile trips takes one hour. The
positive x-direction is to the east. (i) Automobile A travels 50 km due east. (ii) Automobile B travels 50 km
due west. (iii) Automobile C travels 60 km due east, then turns around and travels 10 km due west. (iv)
Automobile D travels 70 km due east. (v) Automobile E travels 20 km due west, then turns around and
travels 20 km due east. (a) Rank the five trips in order of average x-velocity from most positive to most
negative. (b) Which trips, if any, have the same average x-velocity? (c) For which trip, if any, is the
average x-velocity equal to zero?

Answer 1

Explanation:

1. velocity of A = 50KM /Hr

2.velocity of b = -50/hr

3.velocity of c = 60-10/hr = 50 km /hr

4.velocity of D = 70 km /hr

5.velocity of E = -20+20 /hr = 0

a) rank - D >A=C >E >B

2.A AND C

3. E

Answer 2

(a) The rankings based on average velocity are

• (iv) D
• (i) A & (iii) C
• (v) E
• (ii) B

$average \: velocity \: = \frac{displacement}{time}$

The average velocity of each trip per hour are the following :-

(i) 50 km/hr

A moves 50 km to east which is the positive direction.

(ii) -50 km/hr

B moves 50 km to west which is negative direction.

(iii) 50 km/hr

displacement of C = 60 - 10 = 50 km ( since it moves 60 km to east in positive direction and then 10 km to west in negative direction.)

(iv) 70 km/hr

D moves 70 km to east which is the positive direction.

(v) 0 km/hr

Since it travels 20 km to west and then 20 to east, the displacement cancels out and hence total displacement is 0.

(b) Trip (i) of A and (iii) of C have the same average velocities.

(c) Trip (v) of E have average velocity equal to zero.

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