16 Questions
The torque of a force is measured by the quantity r × F.
True
The direction of torque is opposite to the direction of the force.
False
The lever arm of a force represents the horizontal distance from the rotation axis to the line of action of the force.
False
For a body to be in static equilibrium, the sum of all torques must be greater than zero.
False
A single force can cause a body to rotate about an axis.
True
A lever is a mechanism that can only be used to balance a smaller force with a larger one.
False
The branch of physics that deals with the motion of material objects is called kinematics.
False
The average velocity of a particle is defined as the ratio of its displacement to the time interval for this displacement.
True
The unit of velocity measurement is km/h.
False
Systematic error is caused by random factors.
False
The Student's coefficient is determined by the type of error.
True
The downward force F used to try to lift the heavy mass M is the same as the reaction force R at the fulcrum.
False
The moment of a force is the product of the force and its perpendicular distance from the fulcrum.
True
The plank will be in equilibrium when the counterclockwise moments are greater than the clockwise moments.
False
The biceps muscles and the jaws are examples of a lever mechanism in a living organism.
True
The mechanical advantage of the lever is the ratio F/l2.
False
Study Notes
Torque and Rotation
- Torque (τ) is a measure of the tendency of a force to rotate a rigid body about an axis.
- Torque is defined as the cross product of the force (F) and the distance (r) from the axis of rotation: τ = r × F.
- The magnitude of the torque is given by: τ = rFsinθ.
- The direction of τ is that of the advance of a right-handed screw rotated in the direction θ, obtained by rotating r toward F.
Conditions for Static Equilibrium
- The sum of all forces equals zero: ∑F_i = 0.
- The sum of all torques equals zero: ∑T_i = 0.
The Lever
- A lever is a mechanism that allows balancing a larger force by a smaller one.
- A lever consists of a plank that pivots at a point called the fulcrum.
- The product of the force and its perpendicular distance from the fulcrum is called the moment of the force.
- A lever will be in equilibrium when the clockwise and counterclockwise moments are equal.
Kinematics
- Kinematics is the study of motion using the concepts of space and time, without regard to the cause of the motion.
- Average velocity is defined as the ratio of the displacement (∆r) to the time interval (∆t) for this displacement: ∆r = ∆t.
- The unit of velocity measurement is m/s.
Mechanics
- Mechanics is the branch of physics that deals with the motion of material objects and their interaction.
- Kinematics is a subdivision of mechanics that is concerned with the study of motion.
This quiz is about understanding the forces acting on a plank, including the downward force, reaction force, and gravitational force. It covers the concept of equilibrium and how the moment of a force affects the rotation of the plank around the fulcrum.
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