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Part of an electric circuit is shown in the figure. The known resistances are R1 = [R1] Ω and R2 = 15 Ω. The currents in the circuit are i = 2.0 A and i1 = 0.8 A, as indicated. What is the value of the resistance R3 (in Ω)?

A fighter jet of mass 9600 kg is moving at a speed of 72 m/s. If its total energy is 2.60×108 J, how high from the ground is it?

A swimmer dives horizontally off a 500 kg raft. If the diver’s mass is 75 kg and his speed while leaving the raft is 4 m/s, what is the raft speed?

A delivery truck is carrying a 120-kg refrigerator. The refrigerator is 2.20 m tall and 85.0 cm wide. The refrigerator is facing sideways and is prevented from sliding. What is the maximum acceleration that the truck can have before the refrigerator begins to tip over? Assume that the center of gravity of the refrigerator is located at its geometrical center.

Impulse is ___________.

If no forces are acting on a moving object, the object will continue to move with constant:

A crate of a weight of 100 N is held in place on a smooth ramp by a rope parallel to the slope attached to a stake at the top of the ramp. What is the tension in the rope if the angle of inclination of the ramp is 20o?

Which of the following is true about momentum? I. It is a vector. II. It is a product of mass times velocity. III. Impulses are required to change it.  

You and your friend push against a wall. Your friend stops after 10 min, while you push for 5 min longer. Compare the work you and your friend do.