A truck is moving with a constant velocity of 54 km/h. In which direction (angle with the direction of motion of track) should a stone be projected up with a velocity of 20 m/s, from the floor of the truck, so as to appear at right angles to the truck, for a person standing on the earth ?

Question

A truck is moving with a constant velocity of 54 km/h. In which direction (angle with the direction of motion of track) should a stone be projected up with a velocity of 20 m/s, from the floor of the truck, so as to appear at right angles to the truck, for a person standing on the earth ?, cos -1 - 3 4, cos -1 - 1 4, cos -1 2 3, cos -1 3 4

MARKS App · Accepted Answer

Let the stone be projected at an angle α to the direction of motion of truck with a speed of v = 20 m/s. Since the resultant displacement along horizontal is zero. The velocity along horizontal = 0 1 5 + 2 0 cos α = 0 ⇒ cos α = - 3 4 ⇒ α = cos -1 - 3 4

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