PHY101- ASSIGNMENT 1 FALL 2018 IDEA SOLUTION.

Question # 1

a)                  A ball will land at the same time if you drop it straight down from the top of a building or if you throw it out horizontally. Either yes or no explain it.

Ans:    Although one is dropped straight down and one is thrown out horizontally the factor which leads to the balls falling is the gravity and due to gravity they have same acceleration and gravity will be pulling both balls downward at the same rate, they also have same vertical velocities. However, the horizontally thrown ball will have a starting velocity horizontal to that building velocity. The horizontally thrown ball will land at the same time with the same vertical velocity as the dropped ball, but it will have most of its initial velocity too, simple vector addition guarantees that the ball thrown horizontally will have more velocity than the dropped ball because the sum of the two vectors will always be higher than that of single vector.

b)                  Is it true or wrong to say that, Vectors always start at the origin?  Either yes or no justify it.

Ans:    Vectors are quantities that have both magnitudes and directions as indicated by arrows and it is not necessary to take position vector from its origin only. Although a vector has magnitude and direction it doesn’t have position. A vector can start anywhere in the space and the placement of the initial point is arbitrary. Vector quantities are important in the study of motion.

Question # 2

Above, you see a batsman hitting a ball at an angle. What is the magnitude of the net force on the ball along each axis, and what is the ball's acceleration along each axis (along the x and y axes.)?

Ans:

Force along ‘x’ axis

 

Force along ‘y’ axis

 

Mass of a ball:

By entering value of ( g ):

g=9.8ms^-2

so,

Acceleration along ‘x’ axis

By Newton’s second law

Acceleration along ‘y’ axis

By Newton’s second law

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