1. Person X pushes twice as hard against a stationary brick wall as person Y. Wh

Question

1. Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the following statements about the work done on the wall is correct?

a. Person X does twice the work of person Y

b. Person X does does non-zero positive work whereas person Y does zero work

c. Person X does four times the work of person Y

d. Both do zero work

2. A force pushes the cart for 1 s, starting from rest. To achieve the same speed with a force half as much, the force would need to push for
a. 1s
b. 0.25s
c. 2s
d. None of the above

3. A perfectly elastic rubber ball is dropped from a certain height and hits the floor with a downward speed v. Since it is perfectly elastic, the ball bounces back with the same speed v going upward. Which of the following statements about the bounce are correct?
a. The magnitude of the ball's momentum was the same just before and just after the bounce.
b. The ball had the same momentum just before and just after the bounce.
c.None of the above statements are correct.

4. What is the magnitude of the momentum of a 8.0 x102 g javelin traveling at 41 m/s?
a. 33000kg.m/s
b. insufficient information
c. 33kg.m/s
d. 51kg.m/s

5. A vinyl record rotates at 45 revolutions per minute (rpm). What is its angular speed in rad/s?
a. 4.7 rad/s
b. 2.4 rad/s
c. 0.67 rad/s
d. 280 rad/s

Explanation / Answer

1 )

d . Both do zero work

because here displacement is zero

work = force * displacement

2 )

a = F/m

now Force is half

a' = a/2

v = u + at

2s

part 4)

p = mv

p = 8 x 10^2 * 41

p = 32800 = 33000 kg m/s

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.