7. An airplane has a gun that fires bullets straight ahead at the speed of 600 m

Question

7. An airplane has a gun that fires bullets straight ahead at the speed of 600 miles per hour when tested on the ground while the plane is stationary. The plane takes off and flies east at 600 miles per hour. Explain whether each of the following is possible for the pilot to measure: a. When fired directly ahead the bullets move eastward at a speed of 1200 miles per b. When fired in the opposite direction (by turning the gun westward, but not the plane), the bullets drop vertically downward. c. If fired vertically downward (by turning the gun downward, but not the plane), the bullets move eastward at 600 miles per hour while they fall

Explanation / Answer

a) When fired in the East : yes

It is said in newton’s first law (law of inertia) no object can change it state of rest or its uniform motion unless a force acts upon it

The bullets and the gun attached to the plane are already travelling at a speed of 600 mph, when fired in the direction of the motion the bullet will move from the plane at 600 mph. So, for an observer on land it would seem that the bullet is moving with a speed of 1200 mph. And if the pilot could measure the speed of the bullet moving away from him, he could add it to the speed of the plane and find it to be 1200 mph

b) When fired in the west : yes

Yes from the bullet’s applied speed will be cancelled out by the speed provided by the motion of the plane. The object will be under uniform accelerated motion due to gravity

c) When fired downwards : yes

In this scenario the object will have two dimensional movement. The velocity provided by the plane (in the east) and the velocity provided by firing (downwards)

The downward direction the gravity increases its speed towards earth. But there is no acceleration in the horizontal direction, so the bullet will continue to move at the same speed and fall on the earth

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