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NOTE: Material in this section of the website is being prepared based on the Draft Australian Physics Curriculum developed by ACARA (Australian Curriculum, Assessment and Reporting Authority). The material itself and/or the arrangement of this material may change as the Australian Physics Curriculum reaches implementation stage in 2012-2013.
UNIT 1 - MOTION & ENERGY WORKSHEETS
VECTOR ANALYSIS WORKSHEET No.1Answers
are supplied. Simply click on the word "answers" at the end of
each question. 1.
A ship is heading due west at a steady speed of 15 km/h.
A current of 3 km/h is running due south.
Calculate the velocity of the ship relative to the seabed.
(Hint: The velocity of the ship plus the velocity of the current will add
up to the total velocity of the ship relative to the seabed.) Answers 2.
Two tractors pull on a large boulder in an effort to shift it out of the
way of a new fence line. One
tractor pulls with a force of 3000 N west and the other tractor pulls with a
force of 2500 N in a southerly direction because of the terrain.
Determine the resultant force acting on the boulder.
If the boulder has a mass of 1000 kg calculate the acceleration of the
boulder due to the resultant force acting on it. Answers 3.
Three coplanar horizontal forces each of magnitude 10 N act on a body of
mass 5 kg as shown below. Determine
the magnitude of the net force acting on the body and the magnitude of the
resultant acceleration. Answers 4.
If vector A = 5 N north and vector B = 10 N east, find the resultant of
vector A – vector B. Answers 5.
A submarine is travelling at 20 km/h due east.
A short time later it is travelling due north at 15 km/h.
Calculate the change in velocity of the submarine. Answers 6.
An F-117A Nighthawk stealth fighter jet has a true airspeed of 1000 km/h due east.
There is a cross wind blowing in a direction E60oS at 100
km/h. Calculate the velocity of the
jet relative to the ground. (Hint:
You will need to use the cosine & sine rules if you intend to do this
question mathematically.) Answers 7.
A sled of mass 10 kg sits on a horizontal surface as shown below.
8.
A barge of total mass 300 kg is pulled by a single rope attached to a
tugboat of mass 1000 kg. If the
drag on the tug and the barge is one-tenth of their respective weights, and the
total forward force exerted by the tug is 5130 kg force (ie 5130 x 9.8 N), find
the magnitude of: a.
the total force resisting the forward motion of the tug and barge; b.
the acceleration of the tug/barge system; c.
the unbalanced accelerating force on the barge; d.
the tension in the towing rope. 9.
An astronaut of mass MA = 80 kg stands on the
horizontal floor of a spaceship moving vertically with acceleration a.
If the acceleration due to gravity on the astronaut is g
= 9.8 ms-2, write a mathematical expression for and calculate the
value of the reaction force R between the astronaut and the floor of the spaceship when: a.
a = 0; b.
a = 8 ms-2
upwards; c.
a = 8 ms-2
downwards.
ANSWERS TO VECTOR ANALYSIS WORKSHEET No.1Just use your browser's back
button to return to the
questions. 1.
15.3 km/h W11.3oS or S78.7oW 2.
Resultant force = 3905 N in a direction of W39.8oS &
acceleration = 3.9 ms-2 in the same direction as the resultant force. 3.
Net force = 20 N & resultant acceleration = 4 ms-2. 4.
11.2 N in a direction of N63.4oW 5.
25 km/h in a direction of N53.1oW 6.
1054 km/h E5oS 7.
Horizontal force to the left on sled is 75 N, which is greater than the
friction force to the right. Therefore
the sled will move to the left with an acceleration of 2 ms-2.
If you did not get the right acceleration, ask yourself how much of the
75 N to the left actually accelerates the sled – all of it or just some of it?
Some of it has to overcome friction! 8.
(a) 1274 N, (b) 37.7 ms-2, (c) 11 307 N, (d) 11 601 N. 9.
(a) R = MA g =
784 N upwards; (b) R = MA g +
MA a
= 1424 N upwards; (c) R
= MA g
- MA a = 144 N upwards. Return to Vector Analysis Worksheet No.1
FORCE – WORKSHEET 11. Describe the typical effects of the following external forces
acting on bodies: a.
Friction between surfaces b.
Air resistance 2.
In each of the following situations, forces act to cause a change in the
velocity of a vehicle (car). Outline (ie sketch in general terms; indicate the main
features of) the forces involved: a.
Coasting along a level road with no pressure on the accelerator b.
Pressing on the accelerator c.
Pressing on the brakes d.
Passing over an icy patch on the road e.
Climbing hills f.
Descending hills g.
Following a curve in the road 3.
Explain the difference between “mass” and “weight”. 4.
An unbalanced force of 48N west is applied to a 4 kg cart.
Calculate the cart’s acceleration.
(12ms-2 west) 5.
A 2200 kg car, travelling at 25 m/s south, comes to a stop in 10 s.
Calculate (a) the car’s acceleration and (b) the unbalanced force
required to cause that acceleration. (2.5
ms-2 north & 5500 N north) 6.
Astronauts are placed horizontally in their space capsule during launch.
Use Newton’s First Law to explain why this is a good idea. 7.
A particular pressure on the accelerator of a 4-wheel drive van of mass
2000 kg, travelling along a smooth, level road supplies sufficient force from
the engine to accelerate the van at 5 ms-2.
When this same van travels through soft sand, the same pressure on the
accelerator results in a constant velocity of the van.
Determine the force due to friction acting on the van in the soft sand.
(1 x 104N) 8.
The driver’s handbook in a particular country states that the minimum
safe distance between vehicles on the road is the distance a vehicle can travel
in 2 s at constant speed. Assume
that a 1200 kg car is travelling south at 72 km/h when the truck ahead crashes
into a northbound truck and comes to a sudden stop. a.
If the car is at the required safe distance behind the truck, what is the
separation distance between the car and the truck in metres?
(40m) b.
If the average braking force exerted by the car is 6400 N north, how long
would it take the car to stop? (3.75s) c.
What additional data would you need to obtain to determine whether or not
the car would be involved in a collision. Assume
that the car diver has a reaction time of 0.1s. 9.
The diagram below shows a spring balance connected via two inextensible
strings to two identical masses.
ENERGY - WORKSHEET 11.
A car is travelling at 27 m/s north and has a mass of 1500 kg.
Calculate the kinetic energy of the car.
(5.47 x 105 J) 2.
A 7500 kg truck travelling east at 5 ms-1 collides and
coalesces with a 1500 kg car travelling south-west at 20 ms-1.
Describe the energy transformations that may occur during such a
collision. 3.
Determine the amount of work that must be done by the engine of a 500
kg racing car to change the velocity of the car from 55 ms-1 east to
60 ms-1 east. If this
change in velocity was accomplished in 0.3 s, calculate the acceleration of the
car. Find the net force applied by
the engine to cause this acceleration. (143750
J, 16.67 ms-2, 8335 N) 4.
Determine the kinetic energy of a 300 kg space
probe launched from the surface of Mars, once it has reached escape velocity of
5.1 km/s. (3.90 x 109 J) 5.
An army tank of 2.5 x 104 kg mass has a kinetic energy of
1.25 x 106 J. Calculate
the speed of the tank. (10ms-1)
MOMENTUM – WORKSHEET 11.
A 2200 kg car, travelling at 25 m/s south, comes to a stop in 10 s.
Calculate (a) the initial momentum of the car; (b) the final momentum of
the car; (c) the impulse of the net force applied by the brakes; and (d) the
magnitude of the net force applied by the brakes.
(55000 kgm/s south, 0 kgm/s, 55000 kgm/s north, 5500 N north) 2.
A hammer strikes a nail with a force of 55 N for a period of 0.2 s.
Calculate the impulse of the force.
(11 kgm/s) 3.
For how long must an explosive force of 3.3 x 104 N act on a
stationary bullet of mass 0.15 kg to give it a velocity of 220 m/s?
(0.001 s) 4. A mass of 4 kg experiences a varying force as given in the diagram below. Determine the change in velocity of the mass. (3 m/s)
MOMENTUM
– WORKSHEET 2
1.
In experimental tests run by the manufacturer, a car of mass 1500 kg
travelling at 20 ms-1 due east collides with an identical stationary
car. Assuming that all of the
kinetic energy of the moving car is transferred to the stationary car during the
collision, describe quantitatively and qualitatively the expected results of the
collision. 2.
Laboratory Trolley Car A has a mass of 0.9 kg and Laboratory Trolley Car
B a mass of 0.5 kg. For each of the
situations below, describe quantitatively and qualitatively the expected results
of the collision for Car A: a.
Car A moves east at 0.5 ms-1 and collides but does not
coalesce with Car B moving west at the same speed.
After collision, Car B is moving east with a speed of 0.79 ms-1.
(Car A: v = 0.22 m/s west) b.
Car A moves east at 0.5 ms-1 and collides but does not
coalesce with Car B moving east at 0.3 ms-1.
After collision, Car B is moving east with a speed of 0.56 ms-1.
(Car A: v = 0.36 m/s east) c.
Car A moves east at 0.4 ms-1 and collides but does not
coalesce with Car B moving west at 0.3 ms-1.
After collision, Car B is moving east with a speed of 0.6 ms-1.
(Car A: v = 0.1 m/s west) d.
Car A moving at 0.3 ms-1 east collides and coalesces with Car
B moving at 0.5 ms-1 west. (Car
A & B: v = 0.014 m/s east) 3.
A car of mass 1300 kg travelling at 25 m/s south, collides with a solid
rock cliff face. Use your knowledge
of force and momentum to describe a possible result of this collision. 4. OPTIONAL: Go to the following URL and test out your answers to question 2 using the collision Java applet provided. (This URL is a link on my Links page.)
REVISION WORKSHEET No.1
1.
Kate is chasing Angela with a large bucket of water.
She runs 100m due east, followed by 100m due north and then 150m due
south. Calculate Kate’s
displacement from her start point at the end of her run. Answers 2.
Brad’s Lamborghini has an initial velocity of 20ms-1 south
and an acceleration of 5 ms-2 south for five seconds.
Determine: a.
the total change in velocity of the car b.
the final velocity of the car after five seconds. 3.
A car changes its velocity from 5 ms-1 south to 12 ms-1
east. Calculate the change in
velocity of the car. Answers 4.
A car of mass 1000kg changes its velocity from 20ms-1 north to
30ms-1 north in 2 seconds. a.
Determine the amount of work done by the engine of the car to achieve
this change in velocity. b.
Calculate the acceleration of the car and the net force applied by the
engine to cause this acceleration. 5.
A truck of mass 5000kg travelling at 15ms-1 is brought to rest
in a distance of 100m. a.
Calculate the average force exerted by the truck’s brakes to achieve
this change in velocity. b.
Identify the energy transformations that occur as the truck’s kinetic
energy is reduced to zero. 6.
A bus travels at constant speed of 12ms-1 around a circular
bend of radius 150m. a.
Determine the centripetal acceleration (magnitude & direction) of the
bus as it negotiates the bend. b.
Calculate the centripetal force acting on the bus (magnitude &
direction), if the mass of the bus is 2000kg. 7.
A ship is heading due west at a steady speed of 15 km/h.
A current of 3 km/h is running due south.
Calculate the velocity of the ship relative to the seabed.
(Hint: The velocity of the ship plus the velocity of the current will add
up to the total velocity of the ship relative to the seabed.) Answers 8.
Two trucks pull on a large boulder in an effort to shift it out of the
way of a new fence line. One truck
pulls with a force of 3000 N east and the other truck pulls with a force of 2500
N south-east. a.
Determine the magnitude of the net force acting on the boulder.
(Hint: A scaled vector diagram would be helpful here.) b.
If the boulder has a mass of 500 kg calculate the size of the
acceleration of the boulder due to this net force. 9.
Two railway cars are being used in a structure integrity test.
Car A of mass 900 kg moves east at 25 ms-1 and collides but
does not coalesce with Car B of mass 700kg moving west at 20 ms-1. After collision Car B is moving east with a speed of 30.6 ms-1.
Determine: a.
The total momentum of the system before collision. b.
The total momentum of the system after collision. c.
The speed and direction of Car A after collision. d.
The change in momentum of Car A as a result of the collision. e.
The average force acting on Car A, given that the change in momentum took
1.5 seconds. 10.
Study the graph below, which shows the velocity of a vehicle over a
period of time. a.
The average speed of the vehicle from t = 2s to t = 4s. b.
The instantaneous speed of the vehicle at t = 3s. c.
The acceleration of the vehicle from t = 2s to t = 4s. d.
The total distance covered from t = 0 to t = 4s.
ANSWERS TO REVISION WORKSHEET No.1:Just use your browser's back
button to return to the
questions. 1.
111.8m E26.6oS 2.
(a) 25ms-1 South; (b) 45ms-1 South 3.
13ms-1 E22.6oN 4.
(a) 2.5 x 105 J; (b) 5ms-2 north and
5000N north. 5.
(a) 5625N in opposite direction to original motion; (b) kinetic
energy is transformed into sound & heat energy. 6.
(a) 0.96ms-2 towards centre of circular bend; (b)
1920N in same direction as the centripetal acceleration. 7.
15.3 km/h W11.3oS (or S78.7oW) 8.
(a) 5000N; (b) 10ms-2 9.
(a) 8500Ns East; (b) 8500Ns, East; (c) 14.35ms-1
West; (d) 35 415Ns, West; (e) 23 610N, West. 10. (a)
2ms-1; (b) 1.8ms-1; (c) 2ms-2 in opposite
direction to motion; (d) 12m.
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