A stone thrown upward rose by 10 m in 1.4 s and fell to the ground in the same time.

A stone thrown upward rose by 10 m in 1.4 s and fell to the ground in the same time. Determine the modulus of the mean velocity by treating it as a scalar and as a vector.

Given:

H = 10 meters – the height to which the stone climbed;

t = 1.4 seconds – the time during which the stone rose to the height H;

t2 = 1.4 seconds – the time during which the stone fell from the height H to the ground.

It is required to find the average speed of the body V1 (scalar) and V2 (vector).

To find the average speed, considering it as a scalar, you need to divide the entire path traveled by the time it took this path:

V1 = 2 * H / (t1 + t2) = 2 * 10 / (1.4 + 1.4) = 20 / 2.8 = 7.1 m / s.

To find a vector sum:

When the stone moves upward, its speed is directed upward, and its modulus is:

V up = H / t = 10 / 1.4 = 7.1 m / s.

When the stone moves downward, its speed is directed downward, and its modulus is:

V down = H / t2 = 10 / 1.4 = 7.1 m / s.

Since the vectors Vup and Vdown are equal in magnitude, and opposite in direction, then their sum V2 is equal to zero.

Answer: The average speed when viewed as a scalar is 7.1 m / s, when viewed as a vector is 0.