In the latest Indian Jones film, Indy is supposed to throw a grenade from his ca

Question

In the latest Indian Jones film, Indy is supposed to throw a grenade from his car, which is going 73.0 km/h , to his enemy's car, which is going 120 km/h . The enemy's car is 15.0 m in front of the Indy's when he lets go of the grenade. Part A

If Indy throws the grenade so its initial velocity relative to him is at an angle of 45 above the horizontal, what should the magnitude of the initial velocity be? The cars are both traveling in the same direction on a level road. You can ignore air resistance. Answer in km/h.

Part B

Find the magnitude of the velocity relative to the earth. Answer in km/h.

Explanation / Answer

Here ,

Here ,

for the initial velocity of the grenade is v relative to him

speed of indy , v1 = 73 km/hr

v1 = 20.3 m/s

speed of enemy , v2 = 120 km/hr

v2 = 33.33 m/s

for given angle theta = 45 degree

time of flight ,tf = 2 * v * sin(45)/9.8

and

v^2 * sin(2 * 45)/9.8 = 15 + (33.33 -20.3) * v * sin(45/9.8)

solving for v

v = 18.26 m/s

changing to km/hr

v = 65.7 km/hr

the magnitude of initial velocity relative to indy is 65.7 km/hr

--------------------

part B)

for the relative velocity to earth

relative velocity to earth = 65.7 + 73

relative velocity to earth = 138.7 km/hr

the magnitude of the velocity relative to the earth is 138.7 km/hr

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