Download Unit B Assignment

6/25/2017
P20 Unit 2 – Forces
UA pt. A
Name: _______________
Date: _______________
1. Why does a child on a toboggan fall backward when the toboggan is given a sharp tug?
(2 marks)
2. If you get to your feet in a canoe and move towards the front, the canoe moves in the
opposite direction. Explain why. (2 marks)
3. A net force of 2.5 x 103 N acts on an object for 5.0 s. During this time, the object
accelerates from rest to a velocity of 48 km/h. What is the mass of the object? (9.4 x 102
kg) (2 marks)
4. Atwood’s Pulley: A 3.0 kg mass is attached to a 5.0 kg mass by a string that passes
over a frictionless pulley. Find the following values when the masses are allowed to hang
freely:
a) acceleration of the system (2.5 m/s2) (2 marks)
b) magnitude of the tension in the string (37 N) (2 marks)
5. A 9.6 kg sled is pulled along firmly packed snow (which is level). If the coefficient of
kinetic friction between the surfaces is 0.11, what is the magnitude of the force of friction
acting on the sled? (10 N) (1 mark)
6. A 20.0 N box is placed on the floor. A force of 3.0 N is required to keep the object
moving at a constant speed. Find the coefficient of kinetic friction between the two
surfaces. (0.15) (2 marks)
7. An 8.0 g bullet traveling at 400 m/s passes through a heavy block of wood in
4.0 x 10-4 s, emerging with a velocity of 100 m/s. Ignore any motion of the wood.
a) With what average force did the wood oppose the motion of the bullet? (-6.0 x 103 N)
(2 marks)
b) How thick is the wood? (1.0 x 10-1 m) (2 marks)
8. Why is the coefficient of kinetic friction always smaller than the coefficient of static
friction? (2 marks)
9. Fletcher’s Trolley: A 5.0 kg mass rests on a level frictionless table and is attached to a
3.0 kg mass by a string that passes over a frictionless pulley. Find the tension in the
string when the masses are released. (18 N) (3 marks)
10. Fletcher’s Trolley: A steel block rests on a level table and is attached to a 5.0 kg
mass by a string that passes over a frictionless pulley. There is 24 N of friction present
between the steel block and the table. If the acceleration of the system is 2.9 m/s2, find
the mass of the steel block. (3.6 kg) (3 marks)
Putnam Industries
Dept. of “Forcing” you to do this unit assignment!
6/25/2017
Use the following diagram to answer the next question.
11. The diagram shows a 1.20 kg cart on top of a table attached to two masses by strings
going over frictionless pulleys. The coefficient of kinetic friction between the cart and the
table is 0.140. If the mass of m is 1.00 kg and the mass of M is 2.00 kg, what is the
acceleration of the cart? (1.94 m/s2) (3 marks)
12. A 10 kg block on a 30º slope. If the coefficient of friction is 0.30 determine the
following:
a) the force of friction. (25 N) (1 mark)
b) the force of gravity parallel to the slope. (49 N) (1 mark)
c) the acceleration of the block down the slope. (2.4 m/s2) (1 mark)
d) The minimum coefficient of friction needed to prevent the block from sliding. (0.58)
(1 mark)
13. If a stationary rock climber with a mass of 70.0 kg is suspended so that
the rope makes an angle 10.0º from the vertical. Determine the tension in
the rope. (676 N) (2 marks)
Putnam Industries
Dept. of “Forcing” you to do this unit assignment!
6/25/2017
P20 Unit 2 UA pt B –
Gravity
Name: _______________
Date: _______________
1. Galileo Galilee (1564 - 1642), Sir Isaac Newton (1643 - 1727) and Henry Cavendish
(1731 – 1810) all played an important role in the development of gravitational theory. In
three paragraphs, explain the contribution each physicist had on our current
understanding of gravity. (6 marks)
2. Show how Newton’s Law of Universal Gravitation can be derived from Newton’s
formula for determining gravitational field strength. After your derivation, explain what
each variable/constant in the formulae stands for. (2 marks)
3. What is the gravitational attraction between two spheres (mass of 70 kg and 50 kg) if
they are 4.0 m apart? How many times stronger will the attraction be if they are only 1.0
m apart? (1.5 x 10-8 N, 16x) (2 marks)
4. a) What is the gravitational field strength on the planet Omega-3 if the planet has a
mass of 1.50 x 1024 kg and its radius is 18 000 km? (0.309 n/kg) (2 marks)
b) Using this value, what is the weight of a 60.0 kg object on this planet? (18.5 N) (2
marks)
c) Draw a diagram of the field lines acting on the planet Omega-3. (2 marks)
5. A ball that weighs 200 N on Earth is moved to a planet that has a mass four times
larger and a diameter three times larger than that of Earths. After the ball is moved, what
is its
a) mass (20.4 kg) (2 marks)
b) weight (88.9 N) (2 marks)
6. The Earth has a radius of 6370 km. An object of mass = 20.0 kg on the surface of the
earth is moved to an altitude of 160 km above the surface of the Earth. What is the weight
of the object at this height? (187 N) (2 marks)
7. Two objects with equal mass are 75.0 cm apart. If the gravitational force between them
is 5.44 x 10-8 N, find the mass of each object. (21.4 kg) (2 marks)
Putnam Industries
Dept. of “Forcing” you to do this unit assignment!