1. Why can't you open a door by pushing on its hinge side?
2. You can do push-ups with either your toes or your knees acting as the pivot about which your body rotates. When you pivot about your knees, your feet actually help you lift your head and chest. Explain.
3. When you begin to walk forward, what exerts the force that allows you to accelerate?
4. A toy top spins for a long time on its sharp point. Why does it take so long for the friction to slow the top's rotation?
1. To open a door, torque must be applied. *torque = force x perpendicular distance* When the door is pushed at the hinge, the distance is zero. So, it cannot be opened.
ReplyDelete2. The weights of my chest and feet exert torques in opposite directions about my knees. They balance one another.
3. Normal force
4. There is almost zero torque because all the frictional force of the top is concentrated on the sharp tip. Without any significant external torque, the top's angular momentum keeps it spinning for a very long time.
1.The force exerted at the hinges produces no torque on them.
ReplyDelete2.The weights of your chest and feet exert torques in opposite directions about your knees and they partially balance one another.
3.The static frictional force from the floor pushes you forward.
4.Any frictional force on the toy top is exerted close to the top's axis of rotation that it exerts almost zero torque. Without any external torque, the top's roatational momentum keeps it spinning for a very long time.
1. To open a door, torque must be applied. Torque = force x perpendicular distance. The door cannot be opened because when the door is pushed at its hinges, the distance is zero.
ReplyDelete2. The weight of your chest and feet exert torques that go in opposite directions. Therefore, they balance each other.
3. Normal force pushes us forward.
4. The top's frictional force is concentrated on the sharp tip. Therefore, there is almost zero torque. Without any significant external torque, the top's rotational momentum keeps it spinning for a very long time.
1. Torque must be applied to open a door. The perpendicular distance of the hinge to the fulcrum is 0; therefore, torque= F x perpendicular distance(which is 0) would equal to 0.
ReplyDelete2. The weight of my chest and your feet exert force in opposite directions from my knees, therefore balancing each other by cancelling each other out.
3. static frictional force
4. The nearer the Ff is t the pivot point, the lesser the torque is to slow the top's rotation
To open a door, torque must be applied. Torque = force x perpendicular distance. The door cannot be opened because when the door is pushed at its hinges, the distance is zero.
ReplyDelete2. The weight of your chest and feet exert torques that go in opposite directions which balances each other.
3. Normal force.
4. The top's frictional force is concentrated on the sharp tip. Therefore, there is almost zero torque.The top spins for a very long time because there is lesser torque to slow the top's rotation.
1.The force exerted at the hinges produces no torque on them.
ReplyDelete2.The weights of your chest and feet exert torques in opposite directions about your knees and they partially balance one another.
3.The static frictional force from the floor pushes you forward.
4.Any frictional force on the toy top is exerted close to the top's axis of rotation that it exerts almost zero torque. Without any external torque, the top's roatational momentum keeps it spinning for a very long time.
-Charina Tin
1. To open a door, torque must be applied. *torque = force x perpendicular distance* When the door is pushed at the hinge, the distance is zero. So, it cannot be opened.
ReplyDelete2. The weights of my chest and feet exert torques in opposite directions about my knees. They balance one another.
3. Normal force
4. Any frictional force on the toy top is exerted so close to the top's axis of rotation that it exerts almost zero torque.
Without any significant external torque, the top's angular momentum keeps it spinning for a very long time.
-Priscilla Ang
1.To open the door, torque must be applied on it. (torque = force * perpendicular distance) When the door is pushed at the hinge perpendicular distance is zero.
ReplyDeleteHence, it cannot be opened
2. The weights of your chest and your feet exert torques in opposite directions about your knees. They partially balance
one another.
3. A static frictional force from the pavement pushes you forward.
4. Any frictional force on the toy top is exerted so close to the top's axis of rotation that it exerts almost zero torque.
Without any significant external torque, the top's angular momentum keeps it spinning for a very long time.
1.) Torque must be applied to open the door.The distance is zero when you push the door.
ReplyDelete2.) The weights of my chest and feet exert torques in opposite directions about my knees. They balance one another.
3.) Normal force pushes you forward.
4.) There would be less torque to slow the top's rotation, if the frictional force is nearer to the pivot point.
1.If you apply force at the hinge, the moment at the hinge would be zero, because forces acting on the hinge wont budge (torque = force * perpendicular distance). thus, the door won't open.
ReplyDelete2.The weights of your chest and feet exert torques in opposite directions about your knees and they partially balance one another.
3. As we walk, our feet exerts downward and backward force to the ground,the ground also exerts a normal force and a static frictional force which pushes us forward.
4.The top's frictional force is concentrated on the sharp tip. Therefore, there is almost zero torque. Without any significant external torque, the top's rotational momentum keeps it spinning for a very long time.
1.It won't move because torque applied here is 0 as the force acting on the door is not perpendicular to it.
ReplyDelete2.This is because the weight of my chest and feet exert torques on opposite directions about my knees, balancing each other.
3.It is just according to the law of interaction, when you exert force upon the ground, the ground also exerts about the same force upon you.
4.Because it only balances using the tip of the top, the friction would affect it less than usual. Also, the force applied to it is close to its center of axis, making it slower to stop the spinning.