Download Newton`s Laws Practice Problems

Unit 4, More About Forces
Worksheet 5
More Practice with Newton’s 2nd Law
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Name_______________________________
Date__________________Period________
Complete the following statement. A newton is defined as the amount of net force which will . . . . .
A net force of 25.0 N is applied to a 2.00 kg mass. What is the acceleration imparted to the mass?
A 16.0 N net force is applied to a 2.00 kg mass. What is the acceleration of the mass?
An athlete exerts a force of on a shot-put so that it experiences a net force of 150 N. It responds with
an acceleration of 2.00 m/s2. What is the mass of the shot put?
A 1.50 kg mass accelerated across a smooth table at 15.0 m/s2. What is the net force applied to it?
What net force gives a 1.00 kg mass an acceleration of 9.81 m/s2?
How massive is an object that can be uniformly accelerated 10.0 m/s2 by a net force of 50.0 N?
Given objects with the masses listed below, determine each object's weight on earth, as well as on a
planet whose gravitational field strength is 19.6 N/kg.
a. 160 g
b. 31kg
a. What is the weight of a10.0 kg piece of iron?
b. What is the mass of an object that weighs 490 N?
c. What would the object in b weigh on the moon, where the gravitational field strength is about 1.6
N/kg?
Boeing has just opened up a new plant on the moon and it is important that the materials produced on
the lunar plant match those being produced on the earth. Standard slotted masses are sent to the moon
as well as a perfectly frictionless 10.0 kg block that can be slid along a horizontal table with zero
frictional resistance. A stopwatch and a meter stick are sent as well. Lunar and earth laboratory
investigators have identical spring scales which are calibrated in both newtons and kilograms.
If the ten kilogram block is accelerated to the right with a force of 10.0 N to the right.
a. What acceleration will it have on the moon? b. On the earth?
The ten kilogram mass is now hung on the spring scale. What is its weight as shown by the spring scale
on the moon? On the earth? Are the values shown on the scale correct for their respective situations?
Two giant iron spheres (much too heavy to lift) are suspended from a 15.0 m chain. The spheres
appear identical but one is actually solid while the other is hollow. Design an experiment which will
allow you to identify which is which. Identify whether or not your test uses the concepts of
comparative mass, weight, neither or both. Would your test work in a zero-g environment? Explain!!!
A 1500 kg car accelerates uniformly from rest to 15.0 m/s in 5.00 sec. How much net force was
required? (Remember: acceleration = change in velocity/change in time).
©Modeling Workshop Project 2006/A TIME for PHYSICS FIRST
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Unit 4 WS 5, More About Forces, v1.0
Directions: For each of the problems that follow, include the following:
a. a diagram of the physical situation in which you identify your system
b. a properly scaled and labeled force diagram
c. the given information and what you are trying to find
d. an interpretation of the net force from the force diagram using symbols
e. the equation(s) in original form
f. any algebraic manipulation(s) required on the equation
g. substitution into the final version of the equation (including units)
h. the final answer with units
i. Be sure to include the direction on all vector quantities.
13. A 1000 kg car experiences a forward push due to the engine of 850 N while experiencing a frictional
resistance of 300 N. a)What is the net force acting on the car? b)What is the acceleration of the car?
14. A 1500 kg car is moving to the right at 27.0 m/s. The engine allows the car to be pushed forward with
a force of 500 N while a frictional force of 800 N opposes the motion of the car.
a. What is the net force acting on the car?
b. Describe quantitatively the motion of the car.
d. How long will it take the car to come to a stop?
15. A car experiences an 800 N force due to the engine while being opposed by a 300 N frictional
resistance. As a result of these forces the car accelerates at 0.500 m/s2 in the direction it is traveling.
What is the mass of the car?
16. A 1000 kg automobile with its cruise control on travels at a constant velocity of 25.0 m/s to the north.
The engine provides a force of 1200 N to the north. What is the magnitude and direction of the
frictional force that opposes the motion of the car?
17. An 85.0 kg fireman slides down a pole. A frictional force of 500 N opposes his motion. Describe
quantitatively(draw a force diagram, determine the net force) the motion of the fireman.
18. An 8.00 kg rocket is fired vertically. The upward force supplied by the rocket's engine is 91.3 N.
Assume that no air resistance acts on the rocket.
For the situation after the rocket has left the launching pad:
a. Draw the physical diagram for the situation and identify your system.
b. Draw (and label) a proper force diagram for this system.
c. From your force diagram, determine the net force acting on the rocket using symbols, not numbers.
d. Determine the gravitational force acting on the rocket.
e. What is the net force accelerating the rocket? What are the direction and magnitude of the net
force/?
e. What is the acceleration imparted to the rocket?
19. A prisoner tries to escape from a 5th story window of a prison by tying strips of bed sheets together to
form a rope. The prisoner has a mass of 80.0 kg. The bed sheet "rope" can withstand a tension force of
no more than 500 N without breaking. What is the minimum acceleration with which the prisoner must
slide down the "rope" if he is not to break the rope and plummet to his death?
20. A string can just hold a 10.0 kg object at rest without breaking. What is the maximum upward
acceleration this string can give to a 5.00 kg block without breaking the string?
©Modeling Workshop Project 2006/A TIME for PHYSICS FIRST
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Unit 4 WS 5, More About Forces, v1.0