A 1200-kg truck travels in a straight line and has a speed 25 m/s in the +x direction when the driver hits the brakes. The truck slows down to 5 m/s in 10 s. Assume that the net force on the truck is constant.
A 500-kg Moon lander has a velocity of 10 m/s downward when it is a certain height above the ground. 1 minute later, it is 1 m from the ground and its speed is 0.5 m/s downward. Assume that the thruster on the lander fires upward with a constant force. Moon's gravitational field strength near its surface is 1.6 N/kg.
A 0.4-kg soccer ball is kicked from a location m (on the ground) with initial velocity m/s. The ball's speed is low enough that air resistance is negligible. Therefore, you can assume that the net force is constant. (Note: the +y direction is defined to be perpendicular to the ground and upward, and the x-z plane is the soccer field. t = 0 is defined to be the instant the ball leaves the foot.)
An electron of mass and initial speed in the –y direction enters a region between charged plates in which the force on the electron is constant, in the –x direction with a magnitude . After the electron travels 5 cm in the -y direction, it exits the region between the plates. At this instant when it exits, what is its momentum and how far has it deflected to the left from where it started?
A 20-kg girl rides on a merry-go-round. She is sitting near the edge of the merry-go-round and is rotating counterclockwise. The +z axis is defined to be perpendicular to the merry-go-round, and the +x and +y axes are in the plane of the merry-go-round. (See figures below.)
At , the velocity of the girl is m/s, and 0.15 s later, her velocity is m/s.
Ad a certain instant, the velocity of a 0.050-kg model rocket is , and all significant forces on the rocket are:
You push a 15-kg box across a somewhat smooth concrete floor as shown below.
You push with a force of 20 N at an angle, with respect to the horizontal, of . If the box moves in the +x direction with a constant speed, what is the force by the floor on the box? (Note: the gravitational force of Earth on the box is .)
In a mass spectrometer (an instrument used in chemistry to measure the mass and therefore identity of unknown atoms) positively charged ions are accelerated between two charged plates. Suppose that a proton is nearly at rest at the positively charged plate on the left. It is accelerated toward a negatively charged plate on the right, as shown below. The plates are 5 cm apart.
The electric force by the charged plates on the proton is in the +x direction. This is the only significant force acting on the proton.
You toss a nerf basketball of mass 0.002 kg into the air. At t = 0, the ball leaves your hand. At t = 0.11 s, the net force on the ball is , its velocity is , and its position is . What is its position at t = 0.13 s?
Suppose that you measure the velocity of a 0.015-kg superball just before it hits the floor and find that its velocity is downward with a magnitude of 4.5 m/s. You also measure its velocity just after it hits the floor and find that it is upward with a magnitude of 3.9 m/s. What is the change in momentum of Earth as a result of the collision with the superball?