Torque
What is the definition of torque? Is torque a vector or a scalar?
Torque is the ability of a force to rotate an object around an axis or axle. Torque has a direction and therefore is a vector.
What is the magnitude of the gravitational force of a 75 kg man standing exactly the distance of the radius from the center of the earth?
736 N
When would the gravitational force between two objects be the least and when would it be the greatest?
least force - small masses that are far apart
greatest force - large masses that are close together
A car traveling at a constant speed is going around a circle with a radius of 70 meters. If it takes 120 seconds to travel around the circle one time, what is the car's average speed?
3.66 m/s
True or False: An object that is experiencing a constant, unbalanced force is accelerating.
True
What is the equation used to solve for torque? What are the units used to measure torque?
Torque Tau = F*r and the units of torque are Nm.
What is the gravitational force that two 15 kg masses separated by a distance of 15 meters exert on each other?
6.67 x 10E-11 N
True or False: The relationship between the distance between two objects and the gravitational force between them is linear.
False
A girl is swinging on a swing has a centripetal acceleration of 6 m/s2. If the length of the chains on the swing are 3.0 meters long, what is the girl's tangential speed?
4.24 m/s
How does the speed of an object traveling in a circle relate to the radius of the circle? Assuming the time it takes for one revolution is the always the same.
speed is directly proportional to the radius of the circle. If the radius doubles, the speed doubles. The equation is v = 2(pi)r / T
What is the magnitude of the torque produced by a 4 N force applied to a door at a perpendicular distance of 0.22 m from the hinge?
0.88 Nm
The force of gravity is a ______ force. It is always ________.
field, attractive
If it takes a car 45 seconds to travel 15 meters around the outside of a circular track, what is the car's average speed?
0.33 m/s
A 72 kg skateboarder is moving down a ramp with a 6.0 m radius. At the bottom of this ramp he reaches a speed of 6.5 m/s. What is the centripetal acceleration of the skateboarder? What is the upward force that keeps him traveling in a circle?
ac = 7.04 m/s2
Fc = 507 N
A cork is traveling in uniform circular motion. Describe the cork's speed, velocity, magnitude of the acceleration, and direction of acceleration as either changing or constant.
Speed - constant
Velocity - changing
Magnitude of Acceleration - constant
Direction of Acceleration - changing
When would torque be at a maximum and at a minimum?
Torque is at a maximum when the force is applied perpendicular to the lever arm. It is 0 when applied parallel to the lever arm.
An astronaut weighs 400 N at the Earth's surface. (A) What would his weight be if he were to double his distance to the Earth's center? (B) What would his weight be if he were to triple his distance? (C) What would his weight be if he were to halve his distance?
(A) Double his distance - decreases by a factor of 1/4; 100 N. (B) Triple his distance - decreases by a factor of 1/9; 44 N. (C) Halve his distance - increases by a factor of 4; 1600 N
The time it takes to go once around a circle is called the ________. It is represented by the variable _____.
Period - T (s)
A pilot is flying a small plane at 25 m/s in a circular path with a radius of 76 meters. If a force of 600 N is needed to maintain this motion, what is the mass of the plane and the pilot?
73 kg
An object is moving in uniform circular motion. Assuming the object is moving clockwise, draw arrows on the circle at four locations showing the direction of the velocity, acceleration, and force.
Velocity vector - tangent to the circle
Acceleration vector - towards the center of the circle
Force vector - towards the center of the circle
If you were loosening a bolt and you needed to increase the torque to free a stuck bolt, what could you do to increase the torque on the bolt?
Increase the length "r" of the lever arm and/or increase the force acting on the lever arm.
Apply the force perpendicular to the lever arm.
Two pool balls, each with a mass of 0.9 kg, have a gravitational force of 3.75 x 10E-11 N between them. How far apart are the pool balls?
1.2 m
In uniform circular motion the forces on the object are always unbalanced or balanced?
Unbalanced
A 0.020 kg rubber stopper is moving in a circle with a radius of 0.5 m. If it takes the stopper 0.89 seconds to complete one circle, what is the stopper's velocity, centripetal acceleration, & centripetal force?
vt = 3.53 m/s
ac = 24.89 m/s2
Fc = 0.5 N
If a ball rolls at high speed out of a circular tube resting on a table, will the ball continue in circular motion once it leaves the tube? Why? What direction will it move in?
No, the centripetal force is no longer acting on the ball. Due to inertia, the ball will move in a straight line out of the tube.