SUPPLEMENTARY QUESTIONS

PHYSICAL QUANTITIES AND UNITS: Vectors.

1. For each of the following physical quantities, write V if it is a vector or S if

it is a scalar.

a. the time taken to cross the road;

b. the distance covered by the billiard ball after being hit by the cue;

c. the change in velocity of a downhill skier as she makes a turn;

d. the electric current in an overhead power line;

e. the kinetic energy of an arrow in flight;

f. the weight of a weightlifter;

g. the pressure inside a bicycle tube;

h. the potential difference across an electric motor;

i. the gravitational field strength on the surface of the Moon.

2. Use the given grids to draw:

a. +

b.

c.

d. 2

Q

P

3. Two boys are dragging an object along level ground by pulling a rope held

horizontally with forces of 150 N and 180 N respectively. What single

force on the rope would have the same effect?

4. Two tugs are pulling on a ship, one with a force of 6.0 kN and the other

with a force of 8.0 kN. The cables from the tugs to the ship are at right

angles to each other. Find the magnitude of the resultant force on the ship,

and the angle that its direction makes with the cable in which the force is

8.0 kN.

5. In a tennis match, a girl receives a serve which is travelling at 30 m s-1

south just prior to hitting her racquet. Immediately after leaving her

racquet it is travelling at 25 m s-1 north. Specify fully the change in

velocity she gave the ball.

6. A cyclist travelling at 12 km h-1 east makes a right hand turn at an

intersection without changing speed. What is his change in velocity?

7. A car changes velocity from 30 m s-1 due East to 16 m s

-1 due South. Mass

of the car = 300 kg.

a. Draw a vector diagram to show the initial and final velocities and the

change in velocity.

b. Calculate the change in velocity.

c. Calculate the change in momentum

8. A crate is pulled along the floor by means of a rope making an angle of 30

with the horizontal, the pull in the rope being 80 N. Calculate the effective

part of the pull in moving the crate, and also the force tending to lift it off

the floor.

9. A ramp rises vertically 3.0 m for every 5.0 m of its length. A body

weighing 100 N is placed on the ramp. Find the component of its weight

a. parallel to the ramp;

b. perpendicular to the ramp.

10. The string of a particular bow is pulled back so that, just before the arrow

is fired, the archer exerts a force of 260 N on the string.

The line of action of the 260 N force makes an angle of 50 with each

section of the string. The entire length NPQ consists of one string.

The tension in the string is T.

a. Indicate on the figure the directions of the tension in the two sections

of the string at point P.

b. Determine the magnitude of tension T in the string.