Physics Answers

A man cycles to his destination with the wind at 8 ms-1

and returns home against

the wind at 4 ms-1

. What is his average speed? (Hint: Let the distance between home

and work

How long will it take a 250-N box initially at rest reach a speed of 36 km/h when a force of 65 N is applied on it? The floor is frictionless.

O 1.2 S

O not among the choices

O 2.3 s

O 4.5 s

O 3.9 S

How much work is done in holding a 15 N sack of potatoes while waiting in line at the grocery store for 3 MInutes.

A force of 486N stretches a spring by 0.08m. What is the force constant of the spring? What force will elongate the spring by 0.09m? What is the potential elastic energy when stretched by 0.18m?

An object 0.3 cm tall is plac 15.5 cm to the left of the vertex of a c mirror with a center of curvature of 24.0 cm. Determine the position, size, orientation and type (real or virtual) of the image.

An object 0.006 meters tall is placed 0.2 meters in front of a concave mirror and an image is formed 5 meters in front of the mirror. What is the focal length of the mirror? What is the height of the image?

An object is 28 centimeters from the center of a silvered spherical glass Christmas tree ornament 4.0 cm in diameter. What is the focal length of the ornament? Is it a concave or convex mirror? Will the image be real or virtual? Will the image be upright or inverted? What are the position and magnification of its image? If the object is 3.0-meter-high, what is the height of the image?

A skydiver who's jumped from an airplane has reached a terminal speed of 40.8 m/s . How long will it take them to fall 478 meters? Round to one decimal places if needed.

A car pulls away from an intersection when the light turns green. After uniformly accelerating for the next 4.0 seconds, the car has travelled a distance of 25 m. The car then proceeds at constant speed.

a) what was the cars acceleration?

b) how fast was the car travelling when it finished accelerating?

c) how long will it take for the car to travel another 25 m at this constant speed?

A truck uniformly accelerates from rest to reach the end of the road with a speed of 40m/s. What's is the trucks acceleration?