Kinematics
Rock X is released from rest at the top of a cliff that is on Earth. A short time later, Rock Y is released from rest from the same location as Rock X. Both rocks fall for several seconds before landing on the ground directly below the cliff. Frictional forces are considered to be negligible. After Rock Y is released from rest several seconds after Rock X is released from rest, what happens to the separation distance S between the rocks as they fall but before they reach the ground, and why? Take the positive direction to be downward.
A. S increases because at all times Rock X falls with a greater speed than Rock Y.
B. S increases because the difference in speed between the two rocks increases as they fall
A. S increases because at all times Rock X falls with a greater speed than Rock Y.
A 5kg object is released from rest near the surface of a planet such that its gravitational field is considered to be constant. The mass of the planet is unknown. After 2s, the object has fallen 30m. Air resistance is considered to be negligible. What is the gravitational force exerted on the 5kg object near the planet’s surface?
75 N
Two asteroids pass each other at a distance of . As they pass, they each experience a gravitational force of . One of the asteroids has twice the mass as the other asteroid.
Calculate the mass of the lighter asteroid.
6.10 X 10^18 kg
Swimmers at a water park have a choice of two frictionless water slides, as shown. Although both slides drop over the same height, h, slide 1 is straight while slide 2 is curved, dropping quickly at first and then leveling out. How does the speed of a swimmer reaching the end of slide 1 compare with , the speed of a swimmer reaching the end of slide 2?
v1 = V2
If you want to double the momentum of a gas molecule, by what factor must you increase its kinetic energy?
4
A student drops a rock from rest at a distance ℎ above the ground such that the rock hits the ground at time t. At what distance above the ground should the rock be dropped such that it hits the ground at a time 2t after it is released from rest?
4h
A satellite orbits Earth. The only force on the satellite is the gravitational force exerted by Earth. How does the satellite’s acceleration compare to the gravitational field at the location of the satellite?
The gravitational field and the acceleration point in the same direction.
or
The magnitudes of the acceleration and the gravitational field strength are equal.
A student attaches a mass to a cord of length and spins it rapidly in a horizontal circle above her head. When the speed of the mass reaches , the cord breaks, and the mass flies off. The student wants to increase the speed to .
What mass would allow the student to increase the speed to without breaking the cord?
m/16
A lightweight object and a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rises to a greater height?
They both slide up the same height.
A 0.10-kg ball, traveling horizontally at 25 m/s, strikes a wall and rebounds at 19 m/s. What is the magnitude of the change in the momentum of the ball during the rebound?
4.4 kg * m/s
A ball is thrown horizontally at 10 m/s. The ball hits the ground 5 s later. From what height was the ball thrown?
125 m
The Earth pulls downward on a pingpong ball with a force of 1N. If this is the "action" force, what is the "reaction" force?
The ping pong ball exerts a force of 1 N on the Earth
An astronaut with a mass of travels to Planet Y280, which has radius and mass . The astronaut has a weight of on the surface of the planet. The astronaut travels a distance of radii above the surface to measure the gravitational field, , at that height.
0.63 m/s/s
If you push twice as hard against a stationary brick wall, the amount of work you do...
remains constant at zero
Two ice skaters suddenly push off against one another starting from a stationary position. The 45-kg skater acquires a speed of 0.375 m/s relative to the ice. What speed does the 60-kg skater acquire relative to the ice?
0.28 m/s
A ball is thrown vertically upward at 29.4 m/s. What is the maximum height the ball reaches?
44.1 m
A 3.3 kg mass is on a rough horizontal surface. It is pressed against a spring (spring constant 333 N/m) so that it is 33 cm from its equilibrium position as shown. What is its acceleration immediately after it is released?
30 m/s/s
Suppose an alien spacecraft were able to capture and move the moon to a new orbit around the Earth that is three times the radius of its current orbit.
What would happen to the magnitude of the gravitational force between the Earth and the moon?
If the net work done on an object is negative, then the object’s kinetic energy...
decreases
A golf club exerts an average horizontal force of 1000 N on a 0.045-kg golf ball that is initially at rest on the tee. The club is in contact with the ball for 1.8 ms. What is the speed of the golf ball just as it leaves the tee?
40 m/s
A bullet is moving at a speed of 367 m/s when it embeds into a lump of moist clay. The bullet penetrates for a distance of 0.0621 m. Determine the acceleration of the bullet while moving into the clay. (Assume a uniform acceleration.)
a = -1.08*10^6 m/s/s
The giant space slug from question 5 has a weight of 5.4 N when it is 1.5 x 10^13 m from the centre of Earth. What is its mass?
3.1 * 10^12 kg
What is the distance from the center of the Moon to the point between Earth and the Moon where the gravitational pulls of Earth and Moon are equal? The mass of Earth is 5.97 × 10^24 kg, the mass of the Moon is 7.35 × 10^22 kg, the center-to-center distance between Earth and the Moon is 3.84 × 10^8 m, and G = 6.67 × 10^-11 N ∙ m2/kg2
3.84 × 10^7 m
A force produces power P by doing work W in time T. What power will be produced by a force that does six times as much work in half as much time?
12P
A 2200-kg auto moving northward at 12.0 m/s runs into a 3800-kg truck which is also moving northward, but at 5.00 m/s. If the vehicles lock bumpers, how fast are they moving just after the collision?
7.57 m/s