Physics Answers

An ambulance driving 20.0 m/s emits a sound wave with a frequency of 500 Hz. As it drives away from a hospital, which of the following is the only possible frequency heard by the medical staff who are standing at the entrance? 

Why is the orbit of the telescope stable nonetheless? What otherforces need to be considered?

Why is it important to position the JWST behind the Earth?

When you are in an elevator, you feel lighter while accelerating downward. The sensation of weight depends on what force?

a. actual weight

b. tension

c. normal force

d. friction

For a car to safely make around the curve during the course of a turn, an automobile doubles its speed. What frictional force must the tires provide?

Group of answer choices

a. ¼ as big the previous force

b. double

c. ½ as big the previous force

d. quadruple

You slide an 800 N table across the kitchen floor by pushing with a force of 100 N. If the table moves at a constant speed, the friction force with the floor must be

a. 800 N.

b. greater than 100 N but less than 800 N.

c. greater than 800 N.

d. 100 N.

1.) To keep a car on track around the curve during the course of a turn, the car doubles its speed. What is the frictional force must the tires provide?

a. quadruple

b. double

c. 1/2 as big the previous force

d. 1/4 as big the previous force

A box is initially at rest on a smooth incline. If an external force is applied upward, the box will be

a. sliding upward

b. sliding up and down the incline

c. stationary

d. sliding downward

1.) Two forces act on a 55-kg box on a smooth level path. One force has magnitude 50 N directed 45 degrees clockwise from the positive x-axis, and the other has a magnitude 50 N at 45 degrees counter-clockwise from the positive x-axis. What is the net force that causes the box in motion?

a. 0

b. 50 N along positive x-axis

c. 100 N to the right

d. 70 N east

2.) You are in an elevator, standing on a scale, and stuck on 14th floor due to brownout. What is the scale reading?

a. zero

b. greater than the actual weight

c. actual weight

d. less than the actual weight

3.) A roller-coaster car has a mass of 500 kg when fully loaded with passengers. At the bottom of a circular dip of a radius 40m, the car has a speed of 16 m/s. What is the magnitude of the force of the track on the car at the bottom of the dip?

a. 4.9 kN

b. 3.2 kN

c. 1.7 kN

d. 8.1 kN

Scleronomous constraints are