SCHOOL OF NATURAL SCIENCES
PHY 1410 – INTRODUCTORY PHYSICS I
JANUARY 2024 INTAKE
TUTORIAL SHEET 5 – WORK, ENERGY AND POWER
1. Define the following;
a. Work done by a constant force
b. Energy
c. Kinetic Energy
d. Potential Energy
e. Power
2. A body of mass 5kg, initially at rest, is moved by a horizontal force of 2N on a smooth horizontal
surface. Find the work done by the force in 10 s.
3. A force of (3𝑖 + 2𝑗 + 4𝑘) N gives a particle a displacement of (2i – 3j + 5k) meters. What is
the work done by the force?
4. A force of (3 + 2𝑥) N, acting on a particle along the x-axis, displaces it from x = 1m to x = 6
m. Find the work done by the force.
5. Use the work-energy theorem to find the magnitude of the force required to accelerate a car
of mass 1,300kg from rest to 25m/s in a distance of 100 m?
6. Two blocks of masses m1 = 4 kg and m2 = 5 kg are connected by a massless string that passes
over a massless frictionless pulley as shown in Figure below. Block m1 is initially at rest on a
smooth horizontal plane while block m2 is at a height h = 0.75 m above the ground. Use
conservation of mechanical energy to find the speed of the masses just before m2 hits the
ground.
7. How much average power in kilowatts and horsepower is required to lift a block of 100kg to
a height of 10 m in 30 s?
8. An elevator fully loaded with passengers has a mass M = 2,000 kg. As the elevator descends,
an almost constant frictional force f = 4,000 N acts against its motion. What power must be
delivered by the motor to descend the elevator at: (a) a constant speed v of 4 m/s, and (b) a
constant acceleration a of 1.5 m/s2 that produces a speed v = at?
PHY 1410 – INTRODUCTORY PHYSICS I
JANUARY 2024 INTAKE
TUTORIAL SHEET 5 – WORK, ENERGY AND POWER
1. Define the following;
a. Work done by a constant force
b. Energy
c. Kinetic Energy
d. Potential Energy
e. Power
2. A body of mass 5kg, initially at rest, is moved by a horizontal force of 2N on a smooth horizontal
surface. Find the work done by the force in 10 s.
3. A force of (3𝑖 + 2𝑗 + 4𝑘) N gives a particle a displacement of (2i – 3j + 5k) meters. What is
the work done by the force?
4. A force of (3 + 2𝑥) N, acting on a particle along the x-axis, displaces it from x = 1m to x = 6
m. Find the work done by the force.
5. Use the work-energy theorem to find the magnitude of the force required to accelerate a car
of mass 1,300kg from rest to 25m/s in a distance of 100 m?
6. Two blocks of masses m1 = 4 kg and m2 = 5 kg are connected by a massless string that passes
over a massless frictionless pulley as shown in Figure below. Block m1 is initially at rest on a
smooth horizontal plane while block m2 is at a height h = 0.75 m above the ground. Use
conservation of mechanical energy to find the speed of the masses just before m2 hits the
ground.
7. How much average power in kilowatts and horsepower is required to lift a block of 100kg to
a height of 10 m in 30 s?
8. An elevator fully loaded with passengers has a mass M = 2,000 kg. As the elevator descends,
an almost constant frictional force f = 4,000 N acts against its motion. What power must be
delivered by the motor to descend the elevator at: (a) a constant speed v of 4 m/s, and (b) a
constant acceleration a of 1.5 m/s2 that produces a speed v = at?
