Problem 1

A ball is thrown horizontally from a cliff at a speed of 20 m/s. What will its speed be after 2s, and after 3s? Does its horizontal speed also change with time? Give reasons.

Problem 2

A cannon has a muzzle speed of 70 m/s. (a) At what angle should it be fired to reach maximum distance R? (b) Calculate R. (c) Calculate the total duration and maximum height to reach R.

Problem 3

The period of revolution of two satellitesS1 andS2 , which revolve around a planet in coplanar circular orbits in the same sense are 2 h and 4 h, respectively. If the radius of the orbit of S, is 10 m, then find the radius of the orbit ofS1.

A ball is tossed off the edge of a cliff with the same speed but at different angles, as shown. From greatest to least, rank the

a. initial PEs of the balls relative to the ground below.

b. initial KEs of the balls when tossed.

c. KEs of the balls when hitting the ground below.

d. times of flight while airborne.

Problem 5

The positions of a satellite in an elliptical orbit are indicated. Rank these quantities from greatest to least.

a. Gravitational force

b. Speed

c. Momentum

d. KE

. PE

f. Total energy (KE + PE)

Problem 6

In projectile motion, if we consider air resistance to be negligible, (a) what should be the shape of the path followed by the projectile? (b) For a projectile motion, if x =v₀ cos t and y = (v₀ sin ) t -1/2gt2, show that the path is parabolic.

Problem 7

A circularly moving object requires a centripetal force. What supplies the centripetal force for satellites that orbit Earth?

Problem 8

In the sketch on the left, a ball gains KE when rolling down a hill because work is done by

the component of weight (F) that acts in the direction of motion. Sketch in the similar component of gravitational force that does work to change the KE of the satellite on the right.

Problem 9

The orbital velocity of Earth about the Sun is 30 km/s. If Earth were suddenly stopped in its tracks, it would simply fall radially into the Sun. A congressional leader suggests firing a rocket loaded with radioactive wastes into the Sun for permanent disposal. For this to occur, with what speed and in what direction with respect to Earth's orbit should the rocket be fired?