A1.3 kg ball drops vertically onto a floor, hitting with a speed of 21 m/s. it rebounds with an initial speed of 9.8 m/s. (a) what impulse acts on the ball during the contact? (b) if the ball is in contact with the floor for 0.0156 s, what is the magnitude of the average force on the floor from the ball?

Astudent is given an assignment to demonstrate diffraction. he takes a photograph of a straw in a glass of water. the straw appears bent at the water level. which best describes this example? a) this is a good example of diffraction. b) this is an example of dispersion and not diffraction. c) this is an example of refraction and not diffraction. d) this is an example of reflection and not diffraction.

Ineed the answer to question 1 , i’m desperate

The first-order reaction a→2b+c has rate constant 0.538 s−1. if the initial concentration of a is 0.867 mol l−1, what is the half-life of the reaction in seconds? remember to use correct significant figures in your answer (round your answer to the nearest hundredth). do not include units in your response.