Question
1. The Serengeti region of central Africa is home to a myriad of animal species, including the impala, Thomson's gazelle, and the fastest land animal, the cheetah. On one particular day, a 64-kg impala is running at 45 km/h due north, and a 25-kg Thomson's gazelle is running at 77 km/h due east. If a chasing cheetah with a mass of 70 kg has twice the momentum as the impala and gazelle combined, find the direction and magnitude of the cheetah's velocity 2. Your young niece is playing tee-ball (baseball for younsters, where the ball is not pitched but hit off a stationary tee) and hits the ball so that it has an initial speed of 11 m/s. If the bat is contact with the ball (m = 145 g) for 6.5 x 10-3 s, what is the average force exerted on the ball by the bat?
Explanation / Answer
1. P_imp = m v = 64 ( 45j) = 2880 kg km/h j
P_gaz = 24 x 77i = 1848 i
p = 2 ( p_imp + P_gaz)
70 v = 2 ( 1848i + 2880j)
v = 52.8i + 82.3j
Magnitude = sqrt(52.8^2 + 82.3^2) = 97.8 km/h ......Ans
direction = tan^-1(82.3/52.8) = 57.3 deg ...ans
