Question

Directions: Read the questions carefully and write your answers in the space 1. Which of the following is the negation of the vector 12 cmi+0 cmj. a) (12 cm,0°) c) (12 cm, 180) b) (12 cm, 90) d) (-12 cm, 1809) 2. Which of the following is the vector (8 cm, 60°) in rectangular coordinates. a) 4 3i+4j c)8i+oj d) 4i+ 4v3j 3. The velocity of a projectile at its highest point is always (o) a Negative c Zero b Positivec d Equal to the initial velocity 4. Circle all scalar quantities. a) time c) acceleration b) speed d) displacement

Answer 1

1.

If a vector is R = Rx i + Ry j

then magnitude |R| = sqrt (Rx^2 + Ry^2)

direction = arctan (Ry/Rx)

Now given that R = 12 cm i + 0 cm j

|R| = sqrt (12^2 + 0^2) = sqrt 144 = 12

Direction = arctan (0/12) = arctan (0) = 0 deg

R = (12 cm, 0 deg)

Correct option is A.

2.

(8 cm, 60 deg)

then Rx = 8*cos 60 deg = 4 cm

Ry = 8*sin 60 deg = 4*sqrt 3 cm

R = 4 i + 4$\sqrt 3$ j

Correct option is D.

3.

Velocity of projectile at the highest point will always be zero.

Correct option is C.

4.

Scalar quantities are which have no direction,

these are: time, & speed

Correct option as A and B

5.

SI unit of mass = kilograms = kg

SI unit of time = second

SI unit of length = meter

Correct option is B.

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