Question

1. susan drops a ball 15 m in 3 seconds. what is the speed of the ball?

a. 5 m
b. 45 m/s
c. 5 m/s
d. 5m/h

9 jill went to the store with her mom. after they loaded the groceries into the car, her mom pushed the cart to her and asked her to put the cart in the return cradle. when jill pushed the cart, she noticed that it went a lot farther than when she was in the store. this happened because
a. they were outside
b. the mass decreased because there were no groceries in it
c. the mass increased because of the friction
d. there was no change, jill got stronger.

1. what is the velocity of a plane that traveled 3,000 km from new york to california in 5 hours?

a. 600 km/h
b. 15,000 km/h west
c. 600 km/h west
d. 15,000 km/h

Explanation:

Question 8

Step1: Recall the speed formula

Speed \(v=\frac{d}{t}\), where \(d\) is distance and \(t\) is time.

Step2: Substitute values

Given \(d = 15m\) and \(t=3s\), then \(v=\frac{15}{3}\)

Step3: Calculate

\(v = 5m/s\)

According to Newton's second law \(F = ma\) (where \(F\) is force, \(m\) is mass, and \(a\) is acceleration). When the cart has no groceries, its mass \(m\) decreases. If the force \(F\) (pushing force) is relatively constant, a smaller mass means a larger acceleration \(a\) (since \(a=\frac{F}{m}\)), so it can go farther. Option a is incorrect as being outside is not the root - cause. Option c is wrong because mass does not increase due to friction. Option d is not in line with the physical principle.

Step1: Recall the velocity formula

Velocity \(v=\frac{d}{t}\), and velocity is a vector (needs direction).

Step2: Substitute values

Given \(d = 3000km\) and \(t = 5h\), then \(v=\frac{3000}{5}\)

Step3: Calculate and add direction

\(v=600km/h\), and the direction from New York to California (west).

Answer:

C. \(5m/s\)

Question 9