1. A pole is held vertically by attaching wires at a height of 13.4 m above the

Question

1. A pole is held vertically by attaching wires at a height of 13.4 m above the ground. The other end of each wire is anchored in the ground at a distance of 9.54 m from the base of the pole. The pole makes a right angle with the ground. What is the length of each wire?

2. A bug crawls 2.25 m along the base of a wall. Upon reaching a corner, the bug's direction of travel changes from south to west. The bug then crawls 3.15 m before stopping. What is the magnitude of the bug's displacement?

3. Carl Lewis set a world record for the 100.0-m run with a time of 9.86 s. If, after reaching the finish line, Mr. Lewis walked directly back to his starting point in 90.9 s, what is the magnitude of his average velocity for the 200.0 m?
4. Water drips from rest from a leaf that is 15 meters above the ground. Neglecting air resistance, what is the speed of each water drop when it hits the ground?
5. The wheels of an automobile are locked as it slides to a stop from an initial speed of 30.0 m/s. If the coefficient of kinetic friction is 0.600 and the road is horizontal, approximately how long does it take the car to stop?
6. A 1.0-kg ball on the end of a string is whirled at a constant speed of 2.0 m/s in a horizontal circle of radius 1.5 m. What is the work done by the centripetal force during one revolution?
7. A 2.5-kg ball and a 5.0-kg ball have an elastic collision. Before the collision, the 2.5-kg ball was at rest and the other ball had a speed of 3.5 m/s. What is the kinetic energy of the 2.5-kg ball after the collision?
8. A bicycle wheel of radius 0.70 m is rotating at an angular speed of 6.3 rad/s as it rolls on a horizontal surface without slipping. What is thelinear speed of the wheel?

9. A meter stick is pivoted at the 0.50-m line. A 3.0-kg object is hung from the 0.15-m line. Where should a 5.0-kg object be hung to achieve equilibrium (the meter stick oriented horizontal and motionless)?
10.
A 1.0-kg wheel in the form of a solid disk rolls along a horizontal surface with a speed of 6.0 m/s. What is the total kinetic energy of the wheel?
11.
Assume that an MX missile goes from rest to a suborbital velocity of 3.50 km/s in 40.0 s. What is its average acceleration in m/s/s?

12.
A powerful motorcycle can produce an acceleration of 3.50 m/s/s while traveling at 90.0 km/h. At that speed the forces resisting motion, including friction and air resistance, total 350.0 N. What force does the motorcycle exert backward on the ground to produce its acceleration if its mass with rider is 245 kg?

13.
Boxing gloves are padded to lessen the force of a blow. Calculate the force exerted by a boxing glove on an opponent's face, if the glove and face compress 6.50 cm during a blow in which the 8.00 kg arm and glove are brought to rest from an initial speed of 10.0 m/s.

14.
Train cars are coupled together by being bumped into one another. Suppose two loaded train cars are moving toward one another, the first having a mass of 140,000 kg and a velocity of 0.300 m/s, and the second having a mass of 125,000 kg and a velocity of -0.120 m/s. What is their final velocity?

15.
Engines are often rated by their torque output. A certain engine produces a maximum torque of 225 ft*lb on its 2.00 cm diameter crank shaft. What is this torque in N*m?

16.
Disregarding air resistance, objects fall at constant

Select one:
a. velocity
b. speed
c. distances each successive second.
d. acceleration
17.
A rock is thrown vertically into the air. At the top of its path, its acceleration in meters per second per second is

Select one:
a. none of these
b. zero
c. greater than 9.8
d. between 0 and 9.8
e. 9.8

18.
A bullet is fired from a gun. The speed of the bullet will be the same as the speed if the recoiling gun

Select one:
a. because momentum is conserved.
b. because momentum and velocity are both conserved.
c. if the mass of the bullet equals the mass of the gun.
d. because velocity is conserved.
e. none of these.
Check
19.
When a car is braked to a stop, its kinetic energy is transformed to

Select one:
a. stopping energy.
b. energy of motion.
c. energy of rest.
d. heat.
e. potential energy.

20.
To kick a football so it won't topple end over end, kick it so the force of impact extends

Select one:
a. above its center of gravity.
b. through its center of gravity.
c. below its center of gravity.

Explanation / Answer

1.

length of pole will be

using pythagoras theoram

L^2 = H^2 + D^2

L = sqrt (13.4^2 + 9.54^2)

L = 16.45 m

2.

Again using pythagoras

D^2 = south^2 + west^2

D = sqrt (2.25^2 +3.15^2)

D = 3.871 m

3.

average velocty = displacement/total time

displacement = final position - initial position = 0 m

average velocity = 0/T = 0 m/sec

4.

v^2 = u^2 +2*a*s

a = 9.81 m/sec^2

s = 15 m

u = 0 m/sec

v = sqrt (u^2 + 2*a*s)

v = sqrt (0^2 + 2*9.81*15)

v = 17.15 m/sec

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