What happened at the start of the Cambrian Period?
A) the first oxygen-producing bacteria appeared
B) the first dinosaurs appeared
C) early humans first appeared
D) an explosion of genetic diversity appeared, leading to the appearance of the first animals
D
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Since evaporation of water from reservoirs is an important water loss mechanism, especially in dry climates, it is important to reduce losses. What measures could you suggest for reducing such evaporation? Are any of these actually feasible?
What will be an ideal response?
A 50.0-kg box is being pushed along a horizontal surface. The coefficient of kinetic friction between the box and the ground is 0.350. What horizontal force must be exerted on the box for it to accelerate at 1.20 m/s2?
A) 60.0 N B) 116 N C) 172 N D) 232 N E) 491 N
In a single-slit diffraction experiment, a beam of monochromatic light passes through a slit of width 11.0 ?m
If the first order dark fringe of the resulting diffraction pattern is at an angle of 4.31°, what is the wavelength of light? A) 827 nm B) 301 nm C) 602 nm D) 402 nm E) 201 nm
A miniature spring-loaded, radio-controlled gun is mounted on an air puck. The gun's bullet has a mass of 7.00 g, and the gun and puck have a combined mass of 150 g. With the system initially at rest, the radio controlled trigger releases the bullet causing the puck and empty gun to move with a speed of 0.530 m/s. What is the bullet's speed?
a. 83.2 m/s b. 75.7 m/s c. 12.4 m/s d. 11.4 m/s e. 296 m/s