WorksheetsFriction
Total questions: 20
Worksheet time: 2hrs 38mins
Static Friction is present only when an object is at rest.
True.
False.
A block is pulled along a rough level surface at constant speed by the force . The figure shows the free-body diagram for the block. FN represents the normal force on the block; and f represents the force of kinetic friction. What is the magnitude of FN?
P
f
2mg
mg
A 27.6 kg block is pulled along a rough level surface at constant velocity by the force . The figure shows the free-body diagram for the block. FN represents the normal force on the block; and f represents the force of kinetic friction. The coefficient of kinetic friction is 0.30, what is the strength of P?
4.0 N
81 N
270 N
27.6 N
A 2.0-N force acts horizontally on a 10-N block that is initially at rest on a horizontal surface. The coefficient of static friction between the block and the surface is 0.50.What is the magnitude of the frictional force that acts on the block?
5 N
8 N
2 N
0 N
A 2.0-N rock slides on a frictionless inclined plane. Which one of the following statements is true concerning the normal force that the plane exerts on the rock?
The normal force is 2.0 N
The normal force is greater than 2.0 N
The normal force is less than 2 N, but greater than 0 N
The normal force is 0 N.
Under what condition(s) will an object be in equilibrium? (Hint: An object can be in static equilibrium or dynamic equilibrium).
Only if the object is at rest can it be in equilibrium.
If the object is either moving with constant velocity or with constant acceleration, it is in equilibrium.
Only if the object is moving with constant acceleration can it be in equilibrium.
If the object is either at rest or moving with constant velocity, it is in equilibrium.
A block of mass M is held motionless on a frictionless inclined plane by means of a string attached to a vertical wall as shown in the drawing. What is the magnitude of the tension in the string?
Mg
Mgcos θ
Mg tan 𝜃
Mg sin 𝜃
A 2.50 kg block is held motionless on a rough inclined plane by means of a string attached to a vertical wall as shown in the drawing. θ=15o and the string is pulling with 10.0 N. What amount of static friction is present?
6.34 N
10.0 N
3.70 N
0 N
A 10-kg block is pushed against a vertical wall by a horizontal force of 100 N as shown in the figure. The coefficient of static friction, 𝜇s, between the block and the wall is 0.60; and the coefficient of kinetic friction, 𝜇k, is 0.40. Which one of the following statements is true, if the block is initially at rest?
The block will slide down the wall because the force of static friction can be no larger than 60 N.
The block will slide down the wall because the coefficient of kinetic friction is less than the coefficient of static friction.
The block will remain at rest because the coefficient of static friction is greater than the coefficient of kinetic friction.
The total force exerted on the block by the wall is directed horizontally.
At a playground, a child (m=30.0 kg) slides down a slide that makes a 42° angle with the horizontal direction. The coefficient of kinetic friction for the child sliding on the slide is 0.20. What is the magnitude of her acceleration during her sliding?
4.6 m/s2
9.8 m/s2
5.1 m/s2
6.4 m/s2
An 74.5-kg baseball player slides into second base. The coefficient of kinetic friction between the player and the ground is 0.52. What is the magnitude of kinetic friction acting in the baseball player during the slide?
Traveling at a speed of 15.5 m/s, the driver of an automobile suddenly locks the wheels by slamming on the brakes. The coefficient of kinetic friction between the tires and the road is 0.750. What is the speed of the automobile after 1.10 s have elapsed? Ignore the effects of air resistance.
A person is trying to judge whether a picture (mass = 1.30 kg) is properly positioned by temporarily pressing it against a wall. The pressing force is perpendicular to the wall. The coefficient of static friction between the picture and the wall is 0.585. What is the minimum amount of pressing force that must be used?
A girl is sledding down a slope that is inclined at 28.6° with respect to the horizontal. The wind is aiding the motion by providing a steady force of 108 N that is parallel to the motion of the sled. The combined mass of the girl and the sled is 60.9 kg, and the coefficient of kinetic friction between the snow and the runners of the sled is 0.190. What is the girl's acceleration?
Static and kinetic friction can be present simultaneously.
True
False.
To set an object in motion kinetic friction must be overcome.
True.
False.
What standard units do we use to communicate a frictional force?
kg
N
m
It is unitless.
What standard units do we use to communicate a coefficient of friction?
kg
N
m
It is unitless.
What is the force of gravity?
9.8 m/s2
The weight of an object. Fg=m*g
It is the mass of an object. In kilograms.
A 20.0 kg penguin slides at a constant velocity of 3.3 m/s down an icy incline. The incline slopes above the horizontal at an angle of 6.0°. Determine the coefficient of kinetic friction.
0.6
0
0.11
0.94
