A cheetah can maintain its maximum speed of 100 km/hr for 30.0seconds. What mini

Question

A cheetah can maintain its maximum speed of 100 km/hr for 30.0seconds. What minimum distance must a gazelle running 80.0 km/hr beahead of the cheetah to escape?

a. 100 m

b. 167 m

c. 70.0 m

d. 83.0 m

4. The distance of the Earth from the sun is 93 000 000miles. If there are 3.15 ´ 107 s in one year, findthe speed of the Earth in its orbit about the sun.

a. 9.28 miles/s

b. 18.6 miles/s

c. 27.9 miles/s

d. 37.2 miles/s

7. A rock is thrown straight up with an initial velocity of 19.6m/s. What time interval elapses between the rock’s beingthrown and its return to the original launch point? (Accelerationdue to gravity is 9.80 m/s2.)

                 a. 4.00 s

                 b. 5.00 s

                 c. 8.00 s

           d. 10.0 s

Explanation / Answer

Maximum speed v =100 km / h = 100 * (5/18 ) m / s

                                                = 27.777 m / s

Time t= 30 s

Speed of gazelle v ‘ = 80 km / h

                                = 80 * (5/ 18 ) m / s= 22.22222 m / s

Relative speed V = v – v ‘ = 5.55555 m / s

So, required distance   S= Vt

                                      = 166.666 m

                                      ~ 167 m

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