Question

**1) A solar collector heats the water in the water tank
of a home. Which energy transformation equation best describes this
situation?**

**a) radiant --> thermal**

**b) radiant --> electrical**

**c) radiant --> gravitational -->
electrical**

**d) radiant --> gravitational -->
thermal**

**2) In which case is negative work done?**

**a) The work done by Earth on a ball as the ball, which
was initially at rest, falls 3.0 m down towards Earth.**

**b) A eastward force is applied to an eastward moving
soccer ball that is already moving at a constant velocity to
increase its speed in that direction.**

**c) A cart is moving at a constant velocity of 10 m/s [W]
when a 0.5 N [downward] force is applied.**

**d) The work done by Earth on an arrow as it is fired 200
m straight up into the air.**

**3) An elevator motor lifts a load of 2500 kg a height of
12.0 m in 3.00 seconds. The energy required by the motor to
accomplish this task is 300000 J. What is the efficiency of the
elevator?**

**a) 10.0%**

**b) 98.0%**

**c) 102%**

**d) 8.17%**

**4) A roller coaster has two vertical loops one after the
other. The roller coaster has a speed of 7.00 m/s at the top of the
first loop with a height of 22.2 m. It then proceeds around the
second vertical loop with a height of 15.0 m. What is the speed of
the roller coaster at the top of the second vertical
loop?**

**a) 7.00 m/s**

**b) 13.8 m/s**

**c) 8.40 m/s**

**d) 11.2 m/s**

**5) The capacity to do work is known as**

**a) work**

**b) efficiency**

**c) energy**

**d) heat**

**6) A person lifts a pail of water of mass of 1.50 kg
from the ground to a deck, 1.00 m above the ground. How much work
was done by gravitational force on the pail of water?**

**a) –14.7 J**

**b) +1.50 J**

**c) –1.50 J**

**d) +14.7 J**

**7) In which case is positive work done?**

**a) A eastward force is applied to an eastward moving
soccer ball that is already moving at a constant velocity to
increase its speed in that direction.**

**b) A cart is moving at a constant velocity of 10 m/s [W]
when a 0.5 N [E] force is applied.**

**c) Earth applies a force on the Moon as the Moon travels
one completion rotation in orbit around Earth.**

**d) The work done by air resistance as a baseball is
thrown horizontally towards the catcher.**

**8) A motorboat has a power output of 32 MW and provides
4.0 MJ of energy in**

**a) 0.12 min**

**b) 0.12 s**

**c) 80 s**

**d) 80 min**

Answer #1

1. (D) As solar collector concentrate heat energy from solar radiations and convert it into thermal radiations

2.(D) The arrow is fired upwards and gravitational force always acts downwards which leads to angle between force and displacement 180°

F×s×cos(180) = -Fs (Negative)

3.(B)

Work done for lifting load= 2500×12×g

W=2500×12×9.8

W=294000

Energy required= 300000

Efficiency= 294000/300000

Efficiency=0.98

Efficiency in percentage= 0.98×100= 98%

5. (C) Energy

6.(A)

Work done by gravitational force= -mgh

W= - 1.5×9.8×1

W= -14. 7 J

7. (A)Force is applied in same direction in which ball is moving.

4,8 are done below

While leaning out a window that is 5.7 m above the ground, you
drop a 0.60 kg basketball to a friend at ground level. Your friend
catches the ball at a height of 1.2 m above the ground. Determine
the following.
(a)
the amount of work done (in J) by the force of gravity on the
ball
J
(b)
the gravitational potential energy (in J) of the ball-earth
system, relative to the ground when it is released
J
(c)
the...

While leaning out a window that is 6.1 m above the ground, you
drop a 0.60 kg basketball to a friend at ground level. Your friend
catches the ball at a height of 1.3 m above the ground. Determine
the following.
(a)
the amount of work done (in J) by the force of gravity on the
ball
( ) J
(b)
the gravitational potential energy (in J) of the ball-earth
system, relative to the ground when it is released
(...

Part 1
While leaning out a window that is 6.5 m above the ground, you
drop a 0.60 kg basketball to a friend at ground level. Your friend
catches the ball at a height of 1.2 m above the ground. Determine
the following.
(a)
the amount of work done (in J) by the force of gravity on the
ball
___________ J
(b)
the gravitational potential energy (in J) of the ball-earth
system, relative to the ground when it is released...

1 a) Starting from rest, a 50 Kg person dives
into water from a height of 80 m above the water
surface. Air resistance is negligible. (Use g= 10 m/s2)
Calculate (A) the diver’s KE just before striking the water surface
(B) the velocity of the diver just before striking the water (C)
the work done by gravitational force on the diver (D) the power
delivered by gravitational force on the diver
b) A ball of mass m=0.2 Kg
sitting...

A 36.5 kg box initially at rest is pushed 4.25 m along a rough,
horizontal floor with a constant applied horizontal force of 150 N.
If the coefficient of friction between box and floor is 0.300, find
the following.
(a) the work done by the applied force
J
(b) the increase in internal energy in the box-floor system due to
friction
J
(c) the work done by the normal force
J
(d) the work done by the gravitational force
J...

Assume the 33 kN roller coaster starts from rest and is launched
with electromagnetic motors along a horizontal section of
track.
It takes 13 m to reach a speed of 27 m/s.
A. What force is applied to the roller coaster during the
launch?(include units with answer)
B. A meter measures the energy input into the motors during the
launch as 0.508 kW-hour. What is the efficiency of the motors?
(%)
C. After the launch, the roller coaster goes straight...

1. A circus performer is practicing riding a motorcycle in the
Globe of Death, a hollow sphere you can ride a motorcycle from
within if you manage to get your motorcycle fast enough. She
estimates the radius to be round 4.0 m. The total mass of her
motorcycle and her is 100 kg. As she safely completed her first
vertical loop, returning to the bottom of the sphere at a speed of
25 m/s, how much force is the globe...

1. Which has the greater kinetic energy, a heavy truck at rest
or a moving roller skate?
a. none of above
b. heavy truck at rest
c. the roller skate at rest
d. The kinetic energies are equal.
2. If a sports car with a mass of 2000 kg travels down the road
with a speed of 10 m/s, its kinetic energy is _______________ kg
(m/s)2
a. 80000
b. 16000
c. 8000
d. 100000
e.none of above
3. A sports...

21) A person carries a 25.0-N rock through the path shown in the
figure, starting at point A and ending at point B. The total time
from A to B is 1.50 min. How much work did gravity do on the rock
between A and B?
A) 625 J
B) 20.0 J
C) 275 J
D) 75 J
E) 0 J
22) A person carries a 2.00-N pebble through the path shown in
the figure, starting at point A and...

Question 1 (1 point)
Which is not necessary in order to do work on an object (use the
scientific definition of work)?
Question 1 options:
There must be a change in momentum.
A net force must be applied to the object.
The object must undergo a displacement.
A component of the force must be in the direction of motion.
Question 2 (1 point)
The change in gravitational potential energy for a 1.9 kg box
lifted 2.2 m is:
Question 2...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 6 minutes ago

asked 21 minutes ago

asked 21 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 2 hours ago

asked 2 hours ago

asked 2 hours ago

asked 2 hours ago