Torque: two equal-magnitude forces are applied to a door at the doorknob. the first force is applied perpendicular to the door, and the second force is applied at 30° to the plane of the door. which force exerts the greater torque about the door hinge?

a. the second force (applied at an angle)
b. the first force (applied perpendicular to the door)
c. both forces exert equal non-zero torques.
d. both forces exert zero torque.

What do you think car designers do if the damage caused by a crash test is too severe?

(2) (a) you have a simple circuit that consists of only a battery (δvbat=1.5v) and two resistors with resistance r1=10ω and r2=5ω, connected in series with each other. what is the current running through the battery? (b) you re-arrange your circuit so now r2 is attached in parallel to r1 rather than in series. what is the current running through the battery? (c) you add an additional resistor r3=7ω on the same branch as r2. what is the current running through the battery? (d) what is the power dissipated in r3?

A75-hp (shaft output) motor that has an efficiency of 91.0 percent is worn out and is to be replaced by a high-efficiency motor that has an efficiency of 95.4 percent. the motor operates 4368 hours a year at a load factor of 0.75. taking the cost of electricity to be $0.12/kwh, determine the amount of energy and money saved as a result of installing the high-efficiency motor instead of the standard motor. also, determine the simple payback period if the pu