4 Physics Questions PLEASE HELP ASAP!!?

could someone help me please?!?!

1. Jim is doing a physics experiment on the rate of cooling of solid objects in air. Which of the following is a variable that is not directly part of his experiment, but should be controlled in his experiment?

initial temperature to which he heats the solid object

temperature of the object with time

time interval over which he makes his measurement

ambient air temperature

2. In William Herschel's experiment that led to the discovery of infrared light, which of the following was his independent variable?

ambient temperature

color of light

time of day

amount of sunlight

3. Sara is doing a projectile motion experiment in which she rolls a ball off a table and measures how long the ball takes to hit the ground. Which of the following is a potential source of error in her investigations?

She rolls the ball from the same height.

She does the experiment with the same equipment, but on different days.

She uses different stopwatches to measure the time.

She uses the same ball.

4. John, Kim, Danny, and Tina all do the same experiment. In the following situations, who has the most reliable information?

Jim does the experiment once and draws a conclusion.

Kim does it twice, gets different results, and draws a conclusion.

Danny does it three times, averages his results, and draws a conclusion.

Tina gets a different result from Jim, thinks she made a mistake, and defers to his conclusion.